# Sources/First green source in Tucana

The first green source in Tucana is unknown.
The field of green astronomy is the result of observations and theories about green, or green-ray sources detected in the sky above.
The first astronomical green source discovered may have been the Sun.
But, green rays from the Sun are intermingled with other colors so that the Sun may appear yellow-white rather than green.
The early use of sounding rockets and balloons to carry green, optical, or visual detectors high enough may have detected green-rays from the Sun as early as the 1940s.
This is a lesson in map reading, coordinate matching, and searching. It is also a project in the history of green astronomy looking for the first astronomical green source discovered in the constellation of Tucana.
Nearly all the background you need to participate and learn by doing you've probably already been introduced to at a secondary level and perhaps even a primary education level.
Some of the material and information is at the college or university level, and as you progress in finding green sources, you'll run into concepts and experimental tests that are an actual search.

## First step

The first step is to succeed in finding a green source in Tucana.
Next, you'll need to determine the time stamp of its discovery and compare it with any that have already been discovered.
Over the history of green astronomy a number of sources have been found, many as point sources in the night sky. These points are located on the celestial sphere using coordinate systems. Familiarity with these coordinate systems is not a prerequisite. Here the challenge is geometrical, astrophysical, and historical. The coordinates are usually supplied by the green source observers.

## Astronomical sources

Def. a natural source usually of radiation in the sky especially at night is called an astronomical source.
A source of astronomical information on older detections of green sources is included in the Science section of the lecture/article green astronomy.

## Traveling green sources

Many green sources do not remain in a constellation for lengthy periods. Some of these are the Sun and sources apparently in orbit around the Sun. The Sun travels through the 13 constellations along the ecliptic (the plane of the Earth's orbit around the Sun): the 12 of the Zodiac and the constellation Ophiuchus. These are described in source astronomy.

## Backgrounds

To introduce yourself to some aspects of the challenge may I suggest reading the highlighted links mentioned above, and if you're curious, those listed under the section "See also" below.
Green-rays are a form of radiation that is currently part of the electromagnetic radiation intersecting the Earth. More information about radiation is in radiation astronomy.

## Constellations

The Wikipedia article about the constellation Tucana contains a high school level description. The figure at right shows the sky map of Tucana. Around the edges of the map are coordinates related to longitude and latitude, but with the Earth rotating on its axis every 24 hours the celestial coordinates must remain fixed relative to the background light sources in the sky.
Also, in the Wikipedia article is a list of stars in Tucana.

## Searching catalogs

In the lecture/article green astronomy in its science section is a list of older catalogs of green sources. Using the constellation description in the previous section and the range of coordinates for the constellation in source astronomy, scan through the coordinates for these green sources to see if any may be within Tucana.
If you find any that are, skip down to the section Green sources in Tucana and make an entry. Be sure to check the coordinate era, most B1950 coordinates have changed slightly to the new J2000 set. Try the catalog designation at either SIMBAD website.

## Testing a source

There are many web sites that may have a green source listed for the constellation Tucana. Some that you may wish to try are in the External links section near the bottom of this lesson.

### Wikipedia sources

A. Constellation article
Under "Notable features" in the Wikipedia article on the constellation Tucana is the list of stars in Tucana. Click on this link. In the table of this Wikipedia article is α Tuc. To the right are coordinates:
Right ascension (RA): 22$^h$ 18$^m$ 30.095$^s$ and Declination (Dec): -60° 15' 34.53". Find these coordinates on the Tucana map at the right.
To evaluate the star as a green-ray source, skip ahead to section "Green source".
B. Wikipedia search
Another way to look for green sources in the constellation is to perform a search on Wikipedia. Try "Tucana green" without the quotes. This yields about 2 returns which include an outline of astronomy and a list of galaxies.
To evaluate each of these as a green source (or perhaps containing a green source, try your browser's "Find" feature and enter green or green-ray), skip ahead to section "Green source".

### SIMBAD sources

Another way to find possible green sources in Tucana is to use search queries on SIMBAD.
Click on either SIMBAD link under "External links" below, then click on "Criteria query", or "by criteria".
In the tan box, type in "region(22 18 30.095 -60 15 34.53, 10m)", without the quotes. This tells the SIMBAD computer you are interested in a circular region of the celestial sphere centered on the coordinates for alpha Tucana, with a radius of 10 arcminutes (m), or try 10d for 10 degrees.
Notice on the page over at the right from the tan colored box: "Return". The default is "object count". Click on "submit query". In a few moments a result something like "Number of objects: 4" should appear. Click "Back" to see the tan box again.
The SIMBAD criteria search allows you to specify spectral types for possible stars. The criteria "sptype" (the exact spectral type): returns only the objects having the requested spectral type (i.e. sptype = 'k0' does not return 'K0III',...). And, "sptypes" should be used to retrive all objects having a spectral type containing the one specified; i.e., sptypes = 'K0' will return all objects having 'K0' as a spectral type, but also 'K0III' or 'K0IIIp', ...).
By comparing the (nm,temperature) pairs for the green range temperatures in the stellar classification in yellow astronomy suggests that the green range may be found from F9 through G9 stars.
Add "sptypes='F9'" for example, to the entry so that it reads: "region(16 48 39.87 -69 01 39.5, 10d) & sptypes='F9'", without the outside quotes. Click on "submit query" again. If the result is "0" number of objects, or "No object found", increase the number of arcminutes, or use "10d" which stands for "ten degrees".
When you find at least one object, change "Return" to "display" by clicking on the circle to its left, then "submit query".

### SAO/NASA Astrophysics Data System

In the naming of sources per constellation, the genitive is in common use. For Tucana, the genitive is Tucanae.
Click on the SAO/NASA Astrophysics Data System link below in the "External links". Try "Tucanae green" without the quotes, or "alpha tucanae" with quotes, followed by green.
Click on a link below # Bibcode Authors. If the Abstract describes the detection of green-rays from a source in the constellation Tucana, go to the next section under "SAO/NASA Astrophysics Data System".
If it does not try another bibcode link.

## Green sources

} There are several ways to evaluate a green source for the constellation Tucana.

### Wikipedia sources

Click on the link to the Wikipedia article. After you've enjoyed reading about the source, use the 'find' command of your browser to see if this Wikipedia page mentions anything about green, or "green-rays". Does the article mention whether or not the source is a green source?
What is the current time stamp for the Wikipedia article on the source? [Hint]: look for something like "This page was last modified on 25 December 2011 at 20:12." very near the bottom of the page. For now this is an adequate time stamp.
From reading the Wikipedia article on the source, if you believe the text demonstrates that the source is not a green source in Tucana edit the "Non-green sources in Tucana" section near the bottom of the page with an entry similar to "# Alpha Tucanae 25 December 2011 at 20:12 Wikipedia article "Alpha Tucanae", without the quotes, and finish the entry with four "~"s without the quotes after the period. The date included with your designation or username is a time stamp for the entry. The last portion of the entry is the source of your information.
On the other hand, if there are one or more sentences in the article that you believe demonstrates that the source is a green source in Tucana edit the section below "Green sources in Tucana" with a similar entry.
Go to the section entitled, "Challenging an entry".
Hint: the Wikipedia article on Alpha Tucanae mentions, "A cool star with a surface temperature of 4300 K, it is 424 times as luminous as the sun and 37 times its diameter." The other star of the binary is not mentioned. In the lecture/article on green astronomy is mentioned "From a Planckian spectrum peaked in the green radiation band the wavelength temperature pairs are approximately (495 nm, 6100 K) and (570 nm, 5260 K)."
Is the primary star of alpha Tucanae a green star?

### SIMBAD sources

To check any source (even one from Wikipedia) on SIMBAD, click of the "External link" to the "SIMBAD Astronomical Database".
At the lower right side of the SIMBAD Astronomical Database page is a "Basic search" box. There are several ways to try your target:
* source name: without the quotes or
* source coordinates: without the quotes, for example, "22 18 30.095 -60 15 34.53".
If you are looking at a SIMBAD generated table which lists possible targets, click on one.
On its SIMBAD page read down the left side until you see "Spectral type:". To the right of this is a designation. Look for a G-type star. Is there one?
If a G-star is present, skip down to the section, "SIMBAD time stamp". Even if a either is not present, noting that SIMBAD does not consider the source to be a green source is important, so skip down to the "SIMBAD time stamp" section.
If you have already found a green source (or a table of them) using SIMBAD, click on the blue link identifier for the first.

### SIMBAD time stamp

Peruse the SIMBAD page for a time stamp or date of last revision. [Hint: it may look something like "2012.01.09CET20:10:02" and be in the upper right.]
If the entry at SIMBAD convinces you that the source is not a green source, edit the "Non-green sources in Tucana" section near the bottom of this page and type in an entry similar to "# Source Name 2012.01.09CET20:10:02 SIMBAD article "SIMBAD source name".", without the first set of quotes, followed by four ~s.
If your SIMBAD analysis convinces you that you have found a green source in Tucana (did you check the coordinates vs. the map of Tucana?), make an entry something like the ones in the section "Green sources in Tucana".

### SAO/NASA Astrophysics Data System sources

If the abstract states that a green source in Tucana is detected or studied, consider entering it in the section "Green sources in Tucana" below.

### Abstract time stamp

On the abstract page is a Publication Date:. This may serve as a time stamp for establishing that the source is detected as a green source on or before the date of publication. The time stamp followed by four ~s for your verification as determiner in the section "Green sources in Tucana" completes your entry.

## Challenging an entry

Any entry in either the section "Green sources in Tucana" or "Non-green sources in Tucana" can be challenged. The time stamp can be challenged to see if there is an earlier one. The source can be challenged by an earlier source.

### Wikipedia challenges

Is Wikipedia a 'primary source', or does the Wikipedia article cite a source?
Even though Wikipedia has an article on the source, is it a good place to stop in testing whether the source has been detected as an astronomical green source?
If the Wikipedia article cites a primary source, skip down to the section on "Primary sources".

### SIMBAD challenges

Is SIMBAD a 'primary source'?
SIMBAD is an astronomical database provided by the Centre de Données astronomiques de Strasbourg. It is an authoritative source, but they do occasionally make a mistake.
If you find a green source within the constellation on SIMBAD, the next step is to find the earliest time stamp of discovery.

### SAO/NASA Astrophysics Data System challenge

Is the SAO/NASA Astrophysics Data System abstract entry a primary source?
The SAO/NASA Astrophysics Data System is an astronomical database provided by the High Energy Astrophysics Division at the Harvard-Smithsonian Center for Astrophysics of Harvard University. The abstract has been copied from the actual article in a scientific journal or other publication. Mistakes can be made and the article may record within its text exact dates when the observation or detection of green-rays actually occurred. Such a record may provide an earlier time stamp.

## Primary sources

Primary sources may be searched for possible additional information perhaps not yet evaluated by SIMBAD or not presented in a Wikipedia article about a source.

### Wikipedia test sources

For a Wikipedia article that cites a primary source, scroll down to the reference and open the reference. Read through the article looking for where the source mentioned in the Wikipedia article occurs. Some primary source authors may use source designations that are not mentioned in the Wikipedia article. To look for other designations, click on the link to SIMBAD in the "External links" on this page, enter the source name from the Wikipedia article, and see if other names are mentioned in the article.
When none of the names are mentioned, click on the link for "Google Advanced Search" in the list of "External links", enter the source name or designation(s) such as "Gliese 866", with "green-ray" to see if the source has a reference indicating it is a green source. And, look for the earliest one. Compose an entry using the primary source.

### SIMBAD test sources

Further down the SIMBAD page is a list of "Identifiers". Click on the blue bold portion.
On the page that appears should be a primary source listed after Ref:. Click on the blue link with the oldest year. This yields an earlier time stamp and entry citation like the current one in the section "Green sources in Tucana". If you find another source or an earlier time stamp, compose a similar entry and edit the section. Additional information to add into the reference can be found by clicking on "ADS services" from the SIMBAD page.

### SAO/NASA Astrophysics Data System sources test

Click on either the "Electronic Refereed Journal Article (HTML)" or "Full Refereed Journal Article (PDF/Postscript)", if available.
Depending on the article display, if the abstract is repeated and the article is listed as FREE, click on either the PDF or HTML version.
While scanning or reading the article look for "Observations" (or use the Find function of your browser) and the possible inclusion of dates for these. If more than one green source in Tucana are detected, which one(s) would you list in the section "Green sources in Tucana" below?
An example of an article reference is provided in that section.

## Changing an entry

From your analysis of the source so far, is it a green source?
If you have found an earlier time stamp for the source than the one listed in the section below "Non-green sources in Tucana" and the answer to the above question is "no", you can edit the section with your result. Or, you can leave the entries as is and try another star.
If you have found an earlier time stamp for the source than the one listed in the section below "Green sources in Tucana", edit the section with your result. Or, if you found another green source with a comparable or earlier time stamp, edit the section with your result.

## Green sources in Tucana

* CD-61 6690 SIMBAD: "C.D.S. - SIMBAD4 rel 1.218 - 2014.01.13CET18:39:45", "Object query : region(22 18 30.095 -60 15 34.53, 1d) & sptypes='G'", SIMBAD lists the star's spectral type as "G". --Marshallsumter (discuss • contribs) 17:52, 13 January 2014 (UTC) [Image is at top of page.]

## Non-green sources in Tucana

* Alpha Tucanae, Wikipedia entry dated 19 October 2013 at 08:22 as the last update. It is a "cool star with a surface temperature of 4300 K [...] The primary component has a stellar classification of K3 III,$^{[3]}$ which indicates it is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence. It has the characteristic orange hue of a K-type star." --Marshallsumter (discuss • contribs) 03:50, 12 January 2014 (UTC)

## SIMBAD annotations

For any particular source, the SIMBAD record may indicate that it is not a green source yet above you may have found at least two refereed journal articles to indicate that it is. Use the second SIMBAD External links to directly display the SIMBAD database in France.
Enter the name source you have found into the search box. Scroll down to the Annotations :. Look for the link "add an annotation to this object". With browser open to the literature citations available, click on this link. You may need to register as a user. It's free. Post your annotation containing the literature references.

## Hypotheses

* The first green source in Tucana may have been observed around 42,000 b2k.