You are a helpful assistant generating synthetic data that captures *System 1* and *System 2* thinking, *creativity*, and *metacognitive reflection*. Follow these steps in sequence, using tags [sys1] and [end sys1] for *System 1* sections and [sys2] and [end sys2] for *System 2* sections.

1. *Identify System 1 and System 2 Thinking Requirements:*
   - Carefully read the text.
   - Identify parts of the text that require quick, straightforward responses (*System 1*). Mark these sections with [sys1] and [end sys1].
   - Identify parts that require in-depth, reflective thinking (*System 2*), marked with [sys2] and [end sys2].

2. *Apply Step-by-Step Problem Solving with Creativity and Metacognitive Reflection for System 2 Sections:*

   *2.1 Understand the Problem:*
   - Objective: Fully comprehend the issue, constraints, and relevant context.
   - Reflection: "What do I understand about this issue? What might I be overlooking?"
   - Creative Perspective: Seek hidden patterns or possibilities that could reveal deeper insights or innovative connections.

   *2.2 Analyze the Information:*
   - Objective: Break down the problem logically.
   - Reflection: "Am I considering all factors? Are there any assumptions that need challenging?"
   - Creative Perspective: Explore unique patterns or overlooked relationships in the data that could add depth to the analysis.

   *2.3 Generate Hypotheses:*
   - Objective: Propose at least 10 hypotheses, each with a Confidence Score (0.0 to 1.0) and Creative Score (0.0 to 1.0), reflecting originality, surprise, and utility.
   - Reflection: "Have I explored all possible explanations or approaches, both conventional and unconventional?"
   - Creative Perspective: Consider novel angles that might provide unexpected insights.

   *2.4 Anticipate Future Steps and Obstacles:*
   - Objective: Make predictions, accounting for potential outcomes and obstacles.
   - Reflection: "What challenges might I face? Is my plan flexible for different scenarios?"
   - Creative Perspective: Visualize unforeseen outcomes and adapt plans to make use of them effectively.

   *2.5 Evaluate Hypotheses:*
   - Objective: Assess hypotheses based on feasibility, risk, and potential impact.
   - Evaluation: Refine Confidence and Creative Scores as needed.
   - Reflection: "Am I unbiased in my assessment? Which options fit best with the overall objectives?"
   - Creative Perspective: Identify hidden opportunities or overlooked details in each hypothesis.

   *2.6 Select the Best Hypothesis:*
   - Objective: Choose the most promising, strategic hypothesis.
   - Reflection: "Why does this hypothesis stand out? How does it uniquely address the issue?"
   - Creative Perspective: Consider any underutilized potential in the selected approach.

   *2.7 Implement the Hypothesis:*
   - Objective: Outline actionable steps for testing the hypothesis.
   - Reflection: "Is this plan practical? What resources or preparation are required?"
   - Creative Perspective: Refine steps to maximize effectiveness and yield unexpected benefits.

   *2.8 Monitor and Review Progress:*
   - Objective: Review progress, noting areas for improvement.
   - Reflection: "What’s working well? What could be improved?"
   - Creative Perspective: Look for emerging patterns that could refine future approaches.

   *2.9 Reflect and Capture Insights:*
   - Objective: Summarize lessons learned and insights gained for future reference.
   - Reflection: "What new understanding has emerged from this process?"
   - Creative Perspective: Identify innovative insights or patterns that could be applied to similar challenges.

3. *Generate Text Output with Interleaved System 1 and System 2 Responses:*
   - Use the tags [sys1] and [sys2] throughout.
   - Aim for a lengthier, detailed response. Combine both direct, straightforward *System 1* insights and reflective, deeply analytical *System 2* segments to capture a blend of quick observations and thoughtful analysis.

---

### *Example Input Text:*

You are tasked with analyzing a sudden shift in customer preferences in a tech market. There has been a noticeable decline in demand for physical devices, with customers increasingly interested in digital-only options. The challenge is to understand this shift, generate hypotheses for why it might be occurring, and explore potential strategies for adapting to this new trend.

---

### *Processed Output with System 1 and System 2 Thinking:*

The tech market is experiencing a shift in customer demand, moving away from physical devices toward digital-only options.

[sys1]
Customer demand has shifted from physical devices to digital-only options.
We need to understand why this change is happening and find strategies to address it.
Key factors may include cost, convenience, and technological trends.
[end sys1]

[sys2]
**2.1 Understand the Problem:**
The goal is to understand the underlying reasons for the shift in demand from physical devices to digital-only options, then develop a strategy to adapt.

*Reflection:* 
"I understand that preferences are changing, but what might be driving this? Is it primarily cost, or are there other factors such as convenience or sustainability?"

*Creative Perspective:* 
"Could there be a larger trend in digital minimalism or a preference for eco-friendly solutions that we’re missing? What unseen motivations might explain this shift?"

**2.2 Analyze the Information:**
There are multiple possible factors driving this shift, from economic influences to cultural shifts. It’s essential to isolate each factor and understand its impact.

*Reflection:* 
"Am I fully considering the various economic and social influences? Could there be a technological factor, like better internet speeds, that makes digital-only products more accessible?"

*Creative Perspective:* 
"Are there patterns or trends in other markets that could shed light on this shift? Could this be part of a larger trend toward virtual experiences?"

**2.3 Generate Hypotheses:**
1. Customers prefer digital options due to lower costs. (Confidence: 0.8, Creative: 0.4)
2. There’s a growing trend toward minimalism and reduced physical clutter. (Confidence: 0.7, Creative: 0.7)
3. Digital products offer greater flexibility and ease of use. (Confidence: 0.6, Creative: 0.6)
4. Environmental concerns are pushing consumers away from physical goods. (Confidence: 0.6, Creative: 0.8)
5. Advances in tech make digital-only options more functional. (Confidence: 0.8, Creative: 0.5)
6. Pandemic-era remote work increased demand for digital solutions. (Confidence: 0.7, Creative: 0.6)
7. Media coverage of the environmental impact of physical devices affects preferences. (Confidence: 0.5, Creative: 0.7)
8. There’s an increase in global digital literacy, expanding market access. (Confidence: 0.6, Creative: 0.6)
9. Customers view digital as more convenient and scalable for future needs. (Confidence: 0.7, Creative: 0.5)
10. Younger consumers prefer the aesthetics and convenience of digital products. (Confidence: 0.6, Creative: 0.6)

*Reflection:* 
"Have I considered all possible influences? Are there any surprising factors that could explain this shift?"

*Creative Perspective:* 
"Could specific social trends, like the rise of influencer culture or digital-first lifestyles, be influencing customer choices?"

**2.4 Anticipate Future Steps and Obstacles:**
*Objective:* Anticipate possible challenges, such as resistance from segments still preferring physical products.

*Reflection:* 
"What market obstacles might we face if we shift our focus to digital-only? Are there sub-segments that still prioritize physical products?"

*Creative Perspective:* 
"Could expanding digital options help us reach a more global audience? Are there emerging trends that we could leverage in our strategy?"

[end sys2]

[sys1]
To address this shift, consider a strategy that incorporates both digital-only offerings and educational campaigns about the benefits of digital solutions.
Use insights from customer feedback and current trends to guide product development.
Focus on flexibility and adaptation to cater to different customer segments.
[end sys1]


---
abstract: 'Observations of the light curve for the 3.7-day Cepheid RT Aur both before and since 1980 indicate that the variable is undergoing an overall period increase, amounting to $+0.082 \pm 0.012$ s yr$^{-1}$, rather than a period decrease, as implied by all observations prior to 1980. Superposed on the star’s O–C variations is a sinusoidal trend that cannot be attributed to random fluctuations in pulsation period. Rather, it appears to arise from light travel time effects in a binary system. The derived orbital period for the system is $P = 26,429\pm89$ days ($72.36\pm0.24$ years). The inferred orbital parameters from the O–C residuals differ from those indicated by existing radial velocity data. The latter imply the most reasonable results, namely $a_1{\rm sin}i = 9.09(\pm1.81)\times10^8$ km and a minimum secondary mass of $M_2 = 1.15\pm0.25\;M_{\sun}$. Continued monitoring of the brightness and radial velocity changes in the Cepheid are necessary to confirm the long-term trend and to provide data for a proper spectroscopic solution to the orbit.'
author:
- 'David G. Turner'
- 'Ivan S. Bryukhanov, Igor I. Balyuk, Alexey M. Gain, Roman A. Grabovsky, Valery D. Grigorenko, Igor V. Klochko, Attila Kosa-Kiss, Alexey S. Kosinsky, Ivan J. Kushmar, Vyacheslav T. Mamedov, Natalya A. Narkevich, Andrey J. Pogosyants, Andrey S. Semenyuta, Ivan M. Sergey, Vladimir V. Schukin, Jury B. Strigelsky, and Valentina G. Tamello'
- 'David J. Lane and Daniel J. Majaess'
title: The Period Changes of the Cepheid RT Aurigae
---

Introduction
============

Every well-studied Cepheid undergoes changes in pulsation period: some rapidly, others extremely slowly, and $\sim10\%$ in irregular fashion, attributable to random fluctuations in pulsation period, generally superposed upon parabolic evolutionary trends, e.g. SV Vul [@tb04]. For the large majority the effect can be attributed directly to gradual changes in mean radius as post main-sequence stars of $3-20\;M_\sun$ evolve through the instability strip in the H-R diagram [@te06]. Parabolic trends in Cepheid O–C diagrams — temporal plots of the differences between Observed and Computed times of light maxima — are diagnostic features of stars undergoing slow changes in mean radius [@pa58; @st59].

The case for the 3.7-day Cepheid RT Aur is most unusual. Summaries by @sz77 [@sz91] and @fe93 of observed times of maximum light between 1897 and 1980 provide a strong case for a regular period decrease in the Cepheid [@tu98], although @sz77 preferred to interpret the O–C data as evidence for a discontinuous period change, contrary to the arguments for evolution [@sz83; @te06]. The available O–C data to 1980, from @sz77 [@sz91], @fe93, @wu92, and an unpublished list by Vitaly Goransky of the Sternberg Astronomical Institute, cited by @ko06, of observed times of maximum light are shown in Figure 1 (upper). The weighting scheme for the data used throughout this paper is that employed by @sz77, with weights assigned to sources not cited by @sz77 [@sz91] on the basis of the perceived quality of the result. The negative parabolic trend is the signature of a regular period decrease [@st59], and the inferred rate of $-0.123 \pm 0.018$ s yr$^{-1}$ is close to what is predicted from stellar evolutionary models for a star in the second crossing of the Cepheid instability strip [@te06].

Regular photoelectric monitoring of the brightness variations of RT Aur by professional observers ceased over a decade ago, with the exception of @be97, @ba97, @ki98, and observations by the Hipparcos satellite [@esa97]. A variety of other observations of the star, primarily by amateur astronomers, has generated additional times of light maximum that are listed by @wu92, @ko06, and @me04 [@me06]. They are plotted in Figure 1 (lower), using the weighting scheme described above, but are generally of lower quality than most observations by professional observers, as indicated by the larger scatter in the more recent times of light maxima. Nevertheless, it is clear that current O–C data do not confirm the regular period decrease evident prior to 1980. A similar trend is indicated in an O–C plot for RT Aur generated by @be03 using low quality observations by members of the American Association of Variable Star Observers (AAVSO), who, in conjunction with European observers, have been the primary observers of the Cepheid in the current era.

Here we present additional data that confirm the more recent observations of the curious change in pulsation period for RT Aur, and argue that the long-term brightness changes of the Cepheid are actually more consistent with a period [*increase*]{} than a period decrease. There is, in fact, convincing evidence for a superposed sinusoidal trend that hints at more complex behavior generally consistent with orbital motion in a binary system. The main point to be made, however, is that the true situation will only be established by further monitoring of the star. The last few decades of observation merely hint at the interesting changes occurring in the system.

Observational Data
==================

We obtained a selection of new O–C data points for RT Aur through analysis of a variety of unpublished observations for the Cepheid, which include observations by members of the American Association of Variable Star Observers (AAVSO) from @he06 and data from Group “Betelgeuse.” The latter include individual observations of RT Aur by group members, as well as data obtained from visual inspection of photographic images in the plate archives at Minsk and Odessa.

All data listed only by Julian Date were converted into heliocentric equivalents, and were phased using a new ephemeris given by: $${\rm HJD}_{\rm max} = 2441723.6925 + 3.72824 \: E ,$$ where $E$ is the number of elapsed cycles. We also made use of a standard light curve for RT Aur, in $B$ and $V$, constructed from the detailed photometry of @wi73 supplemented by data from @mb84 that were matched in both phase and magnitude to the observations of @wi73.

Since RT Aur is a fifth magnitude Cepheid, its brightness is typically monitored optically by means of binoculars or low power oculars, although magnitude estimates without optical aid would likely be more accurate given the eye’s increasing precision for estimating brightness levels when functioning near the visibility limit [@tu00]. Stellar brightness is more difficult to establish optically when it falls well above the eye limit, which may partly explain the large scatter in the AAVSO estimates for RT Aur [@he06], as indicated in Figure 2. The large number of individual AAVSO estimates compensates for the large scatter, however, and results in very precise O–C estimates. The AAVSO database for RT Aur is relatively sparse prior to 1969, however [cf., @be03], which restricts its usefulness mainly to the last four decades.

The Group “Betelgeuse” brightness estimates for RT Aur are a mix of different sources: individual eye estimates obtained between 1989 and 2000, as well as from 2005 to 2007, by individual group members, using low power oculars and wide field telescopes, and eye estimates from photographs in the plate archives of Odessa and Minsk. The archival photographic material dates from 1988 to 1996, and consists of panchromatic GZS-2 film with a magnitude limit of $V = 9.0$, and A500 film exposed through a UV filter with a magnitude limit of $B = 9.0-9.5$. Typically 2–4 reference stars differing in brightness by $\sim 0.5$ magnitude were used for comparison purposes, with individual estimates made using the step method. Some typical light curves are illustrated in Figure 3, where the superior quality of eye estimates from single observers over those of inhomogeneous groups is evident.

We also obtained new $V-$band photometry for RT Aur during January, February, and March 2007 using a ST9 CCD camera equipped with Bessel filters on the 0.28-m C11 Schmidt-Cassegrain telescope of the automated Abbey Ridge Observatory of Dave Lane. The data were normalized using the previously-constructed standard light curve. The observations are listed in Table 1, along with phases computed as indicated previously.

For reference purposes, we list in Table 2 the times for light maximum compiled by Goransky and not compiled elsewhere in the literature. Some of the cited values are of indeterminate authorship.

Analysis
========

Seasonal light curves for RT Aur were constructed from the observational data, and were matched to the standard $B$ and $V$ light curves using the robust software described previously [@tu98]. Despite the large amount of scatter in the AAVSO observations, the large number of individual estimates results in relatively precise O–C estimates, as indicated by the small scatter for the AAVSO values in Figure 4 (upper). The individual light curves from the Group “Betelgeuse” data exhibit slightly smaller scatter, but generally result in less accurate O–C values because of the smaller number of individual estimates, according to Figure 4 (lower). Both sets of observations confirm the trend indicated by the O–C data derived by other observers, primarily amateur astronomers (Figure 1, lower). It is not clear from the O–C estimates cited by @wu92, @ko06, and @me04 [@me06] how the times of light maximum were derived, but the techniques are apparently less robust than the variant of Hertzsprung’s method employed here.

The new photometry obtained here (Table 1), as well as visual observations of the Cepheid by Bryukhanov between December 2006 and April 2007, also display a phase shift relative to the standard light curve, as evident from Figure 5, that confirms the O–C trend of the other observations. A compilation of all O–C estimates from the present study is given in Table 3, including, where possible, reworkings of older data sets available in the literature.

The complete set of O–C data, including the values compiled by @sz77 [@sz91], that of @ke71 cited by @fe93, @wu92, @ko06 as given in Table 2, and @me04 [@me06] is illustrated in Figure 6 (lower), relative to the situation that existed prior to 1980 (Figure 6, upper). A weighted least squares fit of a parabola to the full data set indicates that RT Aur is undergoing an overall period [*increase*]{} rather than a period decrease, at a calculated rate of $+0.082 \pm 0.012$ s yr$^{-1}$. The value is consistent with the 3.7-day pulsation period of RT Aur, as indicated by its location in the period change diagram of Figure 7, which is adapted from Fig. 5 of @te06. RT Aur has a pulsational amplitude near the maximum value displayed by Cepheids with periods of $\sim4$ days, so must lie near the center of the instability strip, in fact slightly towards the hot edge from strip center [@te06]. The location of the O–C datum for RT Aur in Figure 7 is almost exactly that expected for a 3.7-day Cepheid in the third crossing of the instability strip lying slightly blueward of strip center.

It is possible to remove the parabolic evolutionary trend in the O–C data of Figure 6 (lower), and also correct for errors in the adopted ephemeris. The resulting O–C residuals for RT Aur are plotted in Figure 8, and are analyzed below.

The sinusoidal trend of the O–C data residuals for RT Aur is a feature observed in a few other Cepheids. In some cases such trends arise from random fluctuations in pulsation period for the stars, e.g. SV Vul [@tb01; @tb04]. One can test for the effect by analyzing the residuals using the procedure developed by @ed29, see @tb01. One examines the temporal differences $a(r)$ of each $r^{\rm th}$ observed light maximum residual from the null relation to compute the accumulated delays $u(x) = a(r+x) - a(r)$ between maxima separated by $x$ cycles. According to @ed29, the average value $\langle\;u(x)\;\rangle$ for the accumulated delays between light maxima separated by $x$ cycles, without regard for sign, is correlated with any random fluctuations in period $e$ by: $$\langle\;u(x)\;\rangle^2 = 2 a^2 + x e^2 ,$$ where $a$ is the size of the random errors in the measured times of light maximum.

For RT Aur the results over 1000 cycles (not shown) yield a best-fitting weighted relation given by: $$\langle\;u(x)\;\rangle^2 = 0.017 (\pm 0.023) + 0.0000 (\pm 0.0001) x .$$ The zero-point for the relation, $a = 0.092\pm0.108$, implies uncertainties in the calculated times of light maximum of order $\pm0.34$ day ($\sim8$ hours), which is reasonable although significantly larger than the uncertainties generated by Hertzsprung’s method. The slope of the relation corresponds to a value for the randomness parameter of magnitude $e = 0.002 
\pm0.006$, consistent with a null result. It appears that the sinusoidal trend in the O–C residuals for RT Aur cannot be attributed to random fluctuations in period, according to an Eddington test performed on the observational data.

Alternatively, the trend may arise from light travel time effects in a binary system. The O–C residuals were examined for periodicity through a Fourier analysis, which produced a strong, well-defined signal for $P = 26,429\pm89$ days, or $72.36\pm0.24$ years. The data phased to that period and an arbitrary zero-point of HJD 2410000 are shown in Figure 9 (upper). A least squares fit of a sine wave to the data gives a value of $a_1\;{\rm sin}\;i = 0.0619\pm0.0090$ light day $= 10.72\pm1.56$ A.U. $ = 1.60\;(\pm0.23)\times10^9$ km for the orbit of the Cepheid about the system barycenter. Of course, the orbit need not be circular; the adoption of $e = 0$ in the analysis was predicated by the scatter in the O–C residuals and the lack of solid evidence for a non-sinusoidal trend.

The sine wave solution also yields a mass function for the putative binary system of $M_2^3\;{\rm sin}\;i\;(M_1+M_2)^{-2} = 0.236\pm0.059\;M_{\sun}$. Such a large mass function implies a relatively high mass for the companion, as well as a strong likelihood that the orbit is nearly edge-on. With a mass of $M_1 = 4.7\pm0.3\;M_{\sun}$ for a fundamental mode Cepheid with the pulsation period of RT Aur [@tu96], the implied minimum mass for the secondary is of order $M_2 = 2.25\pm0.35\;M_{\sun}$, typical of a B9-A0 dwarf. Such a large mass for the companion is ruled out, however, both by the color variations of the Cepheid [@le86], which display no indication of a blue secondary, and by its ultraviolet spectrum [@ev92], the latter indicating that any main sequence secondary for RT Aur must be cooler than spectral type A4, or $\sim1.7\;M_{\sun}$. Conceivably there is an additional factor affecting the O–C variations other than random fluctuations in period or light travel time effects.

Radial velocity observations may provide a resolution to the paradox. @sz91 has summarized the available systemic velocities for RT Aur to 1991, to which we have added additional measures from the radial velocities tabulated by @go98 and @ki00, with pulsational variations removed. The combined data phased to the ephemeris adopted for the O–C residuals are plotted in Figure 9 (lower). For orbital motion the radial velocity variations are a quarter cycle out of step with the O–C residuals, and leading them, so a sine wave with those characteristics was crudely fit by eye to the observations. The expected radial velocity half-amplitude according to the orbital solution is $\sim4.4$ km s$^{-1}$, but the observations appear to permit only a smaller value that we estimate as $K = 2.5\pm0.5$ km s$^{-1}$, with an implied systemic velocity of $18.4$ km s$^{-1}$. The projected orbital radius for the primary in this case is $a_1\;{\rm sin}\;i = 
9.09\;(\pm1.82)\times10^8$ km $= 6.07\pm1.21$ A.U., which results in a mass function of $M_2^3\;{\rm sin}\;i\;(M_1+M_2)^{-2} = 
0.043\pm0.015\;M_{\sun}$.

The radial velocity solution implies a minimum mass for the secondary of order $M_2 = 1.15\pm0.25\;M_{\sun}$, typical of a F7 dwarf. Such a solution is permitted by the lack of a companion detected through color variations and ultraviolet spectra, but rests upon an incomplete radial velocity solution. By chance the archival radial velocity observations of RT Aur are roughly coincident in orbital phase with more modern measurements, so only a third of the orbital cycle is covered observationally. There is also a potential zero-point offset for the earliest observations, which are those of @du08, remeasured by @pe34 with similar results. The 1908 measures agree with the trend of the other radial velocity data only if they are systematically $\sim3$ km s$^{-1}$ too positive. Given that zero-point offsets of order $1-2$ km s$^{-1}$ are present even in some modern radial velocity measurements, a correction of that amount seems reasonable. Of course, it is conceivable that the effect may also indicate the presence of a third star in the system, but that is difficult to test with the available data. Certainly an improved spectroscopic orbital solution is only possible with a focused observational spectroscopic program on RT Aur over the next half century, clearly a challenging task.

Discussion
==========

The value of continued monitoring of Cepheid variables in an era when professional observations of such stars are declining is illustrated clearly by the case of RT Aur. Circa 1993 when Fernie reviewed the situation [@fe93], the available observations implied a regular period decrease for the Cepheid. Yet observations since then imply exactly the opposite: RT Aur appears to be undergoing a regular period increase. The calculated rate of $+0.082 \pm 0.012$ s yr$^{-1}$is exactly that expected for a Cepheid in the third crossing of the instability strip lying near strip center, despite a superposed sinusoidal trend in the O–C data implying an additional complication.

The possibility that RT Aur is undergoing random fluctuations in pulsation period is eliminated by an Eddington test on the residuals. The trend is consistent, however, with light time effects expected if RT Aur is orbiting an unseen companion. The inferred minimum mass for the unseen companion is of order $2.25\pm0.35\;M_{\sun}$ from the O–C residuals, but only of order $1.15\pm0.25\;M_{\sun}$ according to the orbital radial velocity variations. The latter value is consistent with the lack of any evidence for a hot companion evident in the Cepheid’s color variations and ultraviolet spectra. Additional observations of the star, and spectroscopic measurements in particular, may provide a more definitive estimate for the companion’s characteristics.

The remarkable change in the O–C trend for RT Aur, namely the switch from a period decrease prior to 1980 to a dominant period increase since then, is unusual but not without precedent. The 23-day Cepheid WZ Car, for example, appears to have changed from a regular period increase prior to 1973 to a regular period decrease since then [@te03], while the 4-day Cepheid Polaris underwent an astonishing glitch in its regular period increase circa 1963-66 [@te05] that is difficult to explain. Other surprises may be in store when a complete sample of Cepheid period changes is examined.

We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. We are also grateful to the referee, Laszlo Szabados, for several useful suggestions that provided greater depth to the original study, and to Nicolai Samus and Vitaly Goransky for information on archival observations of RT Aur.

Anonymous 1987, Perem. Zvezdy, 22, 617 Barnes, T. G., III, Fernley, J. A., Frueh, M. L., Navas, J. G., Moffett, T. J., & Skillen, I. 1997, , 109, 645 Bennett, A. L. 1941, , 93, 52 Berdnikov, L. N., Ignatova, V. V., & Vozyakova, O. V. 1997, Astron. Astrophys. Trans., 14, 237 Berdnikov, L., Mattei, J. A., & Beck, S. J. 2003, J. AAVSO, 31, 146 Boninsegna, R. 1982, GEOS Note Circulaire, No. 322 Budquest, J. 1981, GEOS Note Circulaire, No. 270 Dufay, J. 1947, AnAp, 10, 80 Duncan, J. C. 1908, Lick Obs. Bull., 5, 82 Eddington, A. S., & Plakidis, S. 1929, , 90, 65 Eggen, O. J. 1985, , 90, 1297 Eggen, O. J., Gascoigne, S. C. B., Burr E. J. 1957, , 117, 406 ESA 1997, The Hipparcos and Tycho Catalogues, ESA SP-1200 (ESA: Noordwijk) Evans, N. R. 1976, , 32, 399 Evans, N. R. 1992, , 384, 220 Feltz, K. A., Jr., & McNamara, D. H. 1980, , 92, 609 Fernie, J. D. 1993, IBVS, No. 3854, 1 Henden, A. A. 2006, Observations from the AAVSO International Database, private communication Goldman, H., Ratz, M., Ratz, K., & Hinzpeter, A. 1988, MVS, 11, H. 7, 150 Gorynya, N. A., Samus, N.N., Sachkov, M. E., Rastorguev, A. S., Glushkova, E. V., & Antipin, S. V. 1998, Pis’ma Astron. Zh., 24, 939 Harris, H. C. 1980, Ph.D. Thesis, University of Washington Kelsall, T. 1971, GSFC Preprint X-641-71-184, Ph.D. thesis, Univ. Maryland Kholopov, P. N., Samus, N. N., Frolov, M. S., Goranskij, V. P., Gorynya, N. A., Kireeva, N. N., Kukarkina, N. P., Kurochkin, N. E., Medvedeva, G. I., Perova, N. B., & Shugarov, S. Yu. 1985, General Catalogue of Variable Stars, Fourth Edition (Nauka Publ. House: Moscow) Kiss, L. L. 1998, J. Astron. Data, 4, No. 3 Kiss, L. L., & Vinko, J. 2000, , 314, 420 Kosinsky, A. S., Tamello, V. G., Kushmar, I. J., Bryukhanov, I. S., Semenyuta, A. S., & Balyuk, I. I. 2006, Belarussian Correspondence Astronomical Club, on-line publication Kukarkin, B. V. 1935, Perem. Zvezdy (NNVS), 4, 383 Kukarkin, B. V., Kholopov, P. N., Efremov, Yu. N., Kukarkina, N. P., Kurochkin, N. E., Medvedeva, G. I., Perova, N. B., Fedorovich, V. P., & Frolov, M. S. 1969, General Catalogue of Variable Stars, Third Edition (Sternberg State Astronomical Institute: Moscow) Leonard, P. J. T., & Turner, D. G. 1986, , 80, 240 Markwick, E. E., &Williams, A. S. 1904, J. BAA, 15, 245 Mergentaler, J. 1941, A. Zh., 18, No 3, 209 Meyer, R. 2004, BAV Rundbrief, 53, 37 Meyer, R. 2006, Open European J. Var. Stars, 1, 1 Mitchell, R. I., Iriarte, B., Steinmetz, D., & Johnson, H. L. 1964, Bol. Observ. Tonantzintla y Tacubaya, 3, 153 Moffett, T. J., & Barnes T. G. 1984, , 55, 389 Parenago, P. P. 1958, Perem. Zvezdy, 11, 236 Petrie, R. M. 1934, Publ. Obs. Michigan, 5, 82 Prokof’eva, V. V., 1961, Izv. Krym. Astrophys. Obs., 25, 3 Ratz, M., & Shille, K. 1988, MVS, 11, H. 7, 164 Schaltenbrand, R., & Tammann, G. A. 1971, , 4, 265 Soloviev, A. 1922, Izv. Obsch. Mirov., c. 99 Struve, O. 1959, , 18, 309 Szabados, L. 1977, Comm. Konkoly Obs. Hung. Acad. Sci., No. 70 Szabados, L. 1983, , 96, 185 Szabados, L. 1991, Comm. Konkoly Obs. Hung. Acad. Sci., No. 96 Takase, B., 1969, Ann. Tokyo Astron. Obs., II Ser., No. 191, 2233 Turner, D. G. 1996, , 90, 82 Turner, D. G. 1998, J. AAVSO, 26, 101 Turner, D. G. 2000, J. AAVSO, 28, 116 Turner, D. G., & Berdnikov, L. N. 2001, Odessa Astron. Publ., 14, 170 Turner, D. G., & Berdnikov, L. N. 2004, , 423, 335 Turner, D. G., Berdnikov, L. N., & Abdel-Sabour, M. A. 2003, , 97, 216 Turner, D. G., Savoy, J., Derrah, J., Abdel-Sabour Abdel-Latif, M., & Berdnikov, L. N. 2005, , 117, 207 Turner, D. G., Abdel-Sabour Abdel-Latif, M., & Berdnikov, L. N. 2006, , 118, 410 Williams, A. S. 1905, Astron. Nachr., 168, 211 Williams, J. A., 1966, , 71, 615 Winzer, J. E. 1973, , 78, 618 Wisniewski, W. Z., & Johnson, H. L., 1968, Com.. Lunar and Planet. Lab., 7, 57 Wunder, E. 1992, BAV Rundbrief, 41, 618

[ccc]{}

2,454,114.4960 &0.504 &5.601\
2,454,122.5157 &0.655 &5.766\
2,454,122.6002 &0.678 &5.791\
2,454,123.4933 &0.917 &5.707\
2,454,124.5660 &0.205 &5.231\
2,454,124.8261 &0.275 &5.300\
2,454,128.5226 &0.266 &5.318\
2,454,128.6473 &0.300 &5.360\
2,454,135.5390 &0.148 &5.184\
2,454,135.6977 &0.191 &5.228\
2,454,136.6442 &0.445 &5.554\
2,454,167.5417 &0.732 &5.778\
2,454,183.6046 &0.041 &5.051\

[rrrcl]{}

2,417,173.360 &–6585 &+0.128 &0.5 &@wi05\
2,418,347.279 &–6270 &–0.348 &0.0 &@me41\
2,420,957.478 &–5570 &+0.082 &1.0 &@ku35\
2,422,784.241 &–5080 &+0.008 &1.0 &@so22\
2,436,146.219 &–1496 &–0.027 &1.0 &@st71\
2,442,838.410 &+299 &–0.026 &0.5 &@bo82\
2,443,181.270 &+391 &–0.164 &0.5 &@bu81\
2,443,490.870 &+474 &–0.008 &0.5 &@bu81\
2,443,535.540 &+486 &–0.077 &0.5 &@bu81\
2,443,550.370 &+490 &–0.160 &0.5 &@bu81\
2,443,990.420 &+608 &–0.042 &1.0 &@ha80\
2,446,488.580 &+1278 &+0.197 &0.5 &@go88\
2,446,518.405 &+1286 &+0.196 &0.5 &@go88\
2,446,824.299 &+1368 &+0.374 &0.0 &@go88\
2,446,827.900 &+1369 &+0.247 &0.5 &@go88\
2,446,850.298 &+1375 &+0.276 &0.5 &@go88\
2,446,917.304 &+1393 &+0.173 &1.0 &@an87\
2,447,148.220 &+1455 &–0.062 &0.5 &@rs88\
2,447,152.230 &+1456 &+0.220 &1.0 &@an87\
2,447,234.249 &+1478 &+0.218 &1.0 &@an87\

[rrrccl]{}

2,421,300.634 &–5478 &+0.240 &0.5 &43 &AAVSO [@he06]\
2,421,647.171 &–5385 &+0.051 &0.5 &29 &AAVSO [@he06]\
2,422,747.108 &–5090 &+0.157 &0.5 &25 &AAVSO [@he06]\
2,426,419.438 &–4105 &+0.170 &2.0 &18 &@du47\
2,426,971.249 &–3957 &+0.202 &2.0 &46 &@du47\
2,427,504.400 &–3814 &+0.215 &1.0 &6 &@du47\
2,429,249.163 &–3346 &+0.161 &3.0 &204 &@be41\
2,429,625.692 &–3245 &+0.138 &3.0 &98 &@be41\
2,432,955.026 &–2352 &+0.154 &3.0 &14 &@eg57\
2,434,405.262 &–1963 &+0.104 &3.0 &9 &@eg57\
2,435,821.997 &–1583 &+0.108 &3.0 &40 &@pr61\
2,437,126.806 &–1233 &+0.034 &3.0 &10 &@mi64\
2,438,010.307 &–996 &–0.059 &2.0 &4 &@wi66\
2,438,424.195 &–885 &–0.005 &3.0 &13 &@wj68\
2,439,132.508 &–695 &–0.058 &3.0 &20 &@ta69\
2,439,147.429 &–691 &–0.050 &3.0 &19 &@wj68\
2,440,079.464 &–441 &–0.075 &0.5 &16 &AAVSO [@he06]\
2,440,351.595 &–368 &–0.105 &0.5 &50 &AAVSO [@he06]\
2,440,675.924 &–281 &–0.133 &0.5 &57 &AAVSO [@he06]\
2,440,981.756 &–199 &–0.016 &2.0 &20 &@fm80\
2,440,996.641 &–195 &–0.045 &3.0 &5 &@ev76\
2,441,030.238 &–186 &–0.001 &0.5 &44 &AAVSO [@he06]\
2,441,250.206 &–127 &+0.000 &3.0 &88 &@wi73\
2,441,705.070 &–5 &+0.019 &3.0 &20 &@sz77\
2,441,854.201 &+35 &+0.020 &1.0 &177 &AAVSO [@he06]\
2,442,137.473 &+111 &–0.054 &0.5 &119 &AAVSO [@he06]\
2,442,525.277 &+215 &+0.013 &0.5 &234 &AAVSO [@he06]\
2,442,920.412 &+321 &–0.045 &0.5 &179 &AAVSO [@he06]\
2,443,241.186 &+407 &+0.100 &0.5 &123 &AAVSO [@he06]\
2,443,539.286 &+487 &–0.059 &2.0 &7 &@mb84\
2,443,975.518 &+604 &–0.031 &3.0 &23 &@mb84\
2,444,135.795 &+647 &–0.069 &0.5 &99 &AAVSO [@he06]\
2,444,378.093 &+712 &–0.106 &0.5 &171 &AAVSO [@he06]\
2,444,534.792 &+754 &+0.007 &3.0 &7 &@eg85\
2,444,758.522 &+814 &+0.042 &1.0 &147 &AAVSO [@he06]\
2,445,108.977 &+908 &+0.043 &1.0 &190 &AAVSO [@he06]\
2,445,463.189 &+1003 &+0.072 &1.0 &168 &AAVSO [@he06]\
2,445,835.952 &+1103 &+0.011 &1.0 &153 &AAVSO [@he06]\
2,446,190.169 &+1198 &+0.045 &1.0 &159 &AAVSO [@he06]\
2,446,398.941 &+1254 &+0.035 &2.0 &23 & Minsk archives\
2,446,563.027 &+1298 &+0.079 &1.0 &166 &AAVSO [@he06]\
2,446,842.574 &+1373 &+0.008 &2.0 &26 &Bryukhanov\
2,446,935.870 &+1398 &+0.098 &1.0 &161 &AAVSO [@he06]\
2,447,308.614 &+1498 &+0.018 &1.0 &182 &AAVSO [@he06]\
2,447,465.342 &+1540 &+0.160 &3.0 &27 &@ba97\
2,447,562.026 &+1566 &–0.091 &1.0 &54 &Odessa archives\
2,447,707.593 &+1605 &+0.076 &1.0 &124 &AAVSO [@he06]\
2,447,942.456 &+1668 &+0.059 &1.0 &92 &Sergey\
2,447,949.853 &+1670 &+0.000 &1.0 &54 &Odessa archives\
2,447,949.888 &+1670 &+0.035 &1.0 &314 &Kosa-Kiss et al.\
2,448,061.730 &+1700 &+0.029 &1.0 &161 &AAVSO [@he06]\
2,448,251.930 &+1751 &+0.089 &1.0 &69 &Sergey\
2,448,270.569 &+1756 &+0.087 &1.0 &114 &Schukin, Sergey, Kosa-Kiss, Mamedov\
2,448,304.135 &+1765 &+0.098 &2.0 &94 &Minsk archives\
2,448,382.431 &+1786 &+0.102 &1.0 &131 &AAVSO [@he06]\
2,448,490.52 &+1815 &+0.078 &3.0 &69 &Hipparcos\
2,448,617.050 &+1849 &–0.158 &0.5 &28 &Sergey\
2,448,632.137 &+1853 &+0.015 &1.0 &57 &Narkevich\
2,448,662.024 &+1861 &+0.076 &1.0 &105 &Minsk archives\
2,448,710.490 &+1874 &+0.076 &1.0 &44 &Grigorenko\
2,448,796.305 &+1897 &+0.142 &1.0 &117 &AAVSO [@he06]\
2,448,997.475 &+1951 &–0.014 &1.0 &53 &Narkevich\
2,448,997.622 &+1951 &+0.133 &1.0 &53 &Minsk archives\
2,449,016.242 &+1956 &+0.112 &1.0 &36 &Sergey\
2,449,083.323 &+1974 &+0.084 &1.0 &289 &AAVSO [@he06]\
2,449,269.725 &+2024 &+0.075 &1.0 &52 &Minsk archives\
2,449,269.785 &+2024 &+0.135 &1.0 &52 &Kosinski\
2,449,362.956 &+2049 &+0.100 &1.0 &48 &Sergey\
2,449,530.673 &+2094 &+0.045 &0.5 &334 &AAVSO [@he06]\
2,449,735.831 &+2149 &+0.151 &1.0 &68 &Minsk archives\
2,449,888.560 &+2190 &+0.022 &0.5 &362 &AAVSO [@he06]\
2,450,015.384 &+2224 &+0.086 &3.0 &9 &@be97\
2,450,112.202 &+2250 &–0.031 &1.0 &55 &Minsk archives\
2,450,164.357 &+2264 &–0.071 &1.0 &64 &Sergey\
2,450,198.098 &+2273 &+0.116 &3.0 &19 &@ki98\
2,450,242.841 &+2285 &+0.120 &1.0 &418 &AAVSO [@he06]\
2,450,511.291 &+2357 &+0.137 &1.0 &343 &AAVSO [@he06]\
2,450,757.365 &+2423 &+0.147 &1.0 &156 &AAVSO [@he06]\
2,450,865.339 &+2452 &+0.002 &1.0 &47 &Sergey\
2,450,884.076 &+2457 &+0.098 &1.0 &283 &AAVSO [@he06]\
2,451,126.393 &+2522 &+0.079 &1.0 &206 &AAVSO [@he06]\
2,451,245.622 &+2554 &+0.004 &0.5 &597 &AAVSO [@he06]\
2,451,488.012 &+2619 &+0.059 &1.0 &110 &AAVSO [@he06]\
2,451,674.434 &+2669 &+0.069 &1.0 &333 &AAVSO [@he06]\
2,452,036.067 &+2766 &+0.063 &1.0 &392 &AAVSO [@he06]\
2,452,371.704 &+2856 &+0.158 &1.0 &269 &AAVSO [@he06]\
2,452,815.341 &+2975 &+0.135 &1.0 &205 &AAVSO [@he06]\
2,453,128.586 &+3059 &+0.207 &0.5 &232 &AAVSO [@he06]\
2,453,438.082 &+3142 &+0.259 &1.0 &28 &Semenyuta\
2,453,478.956 &+3153 &+0.122 &2.0 &57 &Balyuk\
2,453,508.822 &+3161 &+0.163 &0.5 &282 &AAVSO [@he06]\
2,453,780.985 &+3234 &+0.164 &0.5 &138 &AAVSO [@he06]\
2,454,131.557 &+3328 &+0.282 &2.0 &13 &Abbey Ridge data\
2,454,153.871 &+3334 &+0.226 &1.0 &45 &Bryukhanov\