URANUS OPPOSITION 2012-2013(Opposition on last 2012.09.29th)

1- Abstract :91 drawings (36nights) were performed this present opposition with
150-305mm apertures (July 2012-February 2013).
Uranus exhibited from the August 2012 to February 2013 period
some variabilities accessible visually with the help of light coloured filters (light yellow W8
and sometimes the light blue W82A).
Almost featureless at the beginning with moderate apertures (except the 150mm refractor)
where EZ was only accessible faint fuzzy, then more consistently clearer in yellow light andwith more contrasty and bigger apertures.
Brightenings were collected at some periods in relation with the emergence of a third south
hemisphere band.
On October 2012, EZ seemed to reconstitute but faintly, then deemer on December andgetting a clearer appearance on January 2013.
Clear bright patches appeared brighter on the planet during the emergence of the third south
hemisphere band that was reported on November 2012.
2- Main topics:
2.1- Events:
South polar cap:always captured clearer except on the 23th October 2012, the cap was seen clear bordered
by a thin lighter band and bordered by a darker collar.
South hemisphere:
At the beginning only 2 bands were reported until November where on 21st Nov; 12, then on
2nd-8th Dec.12, 3 bands were reported with brightenings in relation.
On 17th-30th Dec.12 and 1st Jan. 13 the south equatorial band that appeared double on the11th Dec.12 seemed to fade and dilute into the south hemisphere sothat this became faintand fuzzy, light grey.
At the beginning on 15thNov.12 albedo variations were collected on the south equatorial bandin relation with a brightening presence in EZ.
On 11th-16th and 17th, the 3 south hemisphere bands were again collected clearly anddistinctly separated. Still brightenings in relation (probably spot for some).
The last observations 30th Jan.13 and 14th Feb.13 didn’t confirm the 3 bands pattern withregards to the viewing conditions.
EZ, equatorial zone:
Appeared clear on some periods.
EZ also get the tendency to fade with the fading of the 3 bands pattern reported during end
Dec.12 until begin Jan.13.
Except with the use of moderate aperture (150mm refractor excluded) EZ was reported moreor less.

North hemisphere:
The north equatorial band was seen darker, as dark as the polar south cap collar. With EZ,
these are the main features on the planet accessible in first, even with the moderate aperture(as the C8 or the DK180).
Brightenings:
Some of the brightenings could be probably spots (on 24th-25th Jul.12, 11th -17th Jan.13, 26thJan.13) but mainly zones between bands exhibit brightenings or albedo variations in relation
sometimes with band albedo variations (15th Nov.12).
Blue colour observations:
Normally the planet disk is featureless in that field; however, on some period the south polar
cap collar and the north equatorial band were reported faintly. This is probably in correlation
with the planet activity.
2.2- Comments:
In spite of the few reports, the coverage needs to be improved in order to verify someassessments suggested above through the “events” observed. This would make stronger theconclusions brought here.
What is obvious:- Uranus is not a featureless planet in visual mode,- Uranus exhibits pattern variations that are obvious,- Uranus pattern changes involve some albedo variations and contrast variations that need tobe followed narrowly through a larger coverage.
Hope the next opposition will occur in relation with more better weather local conditions. Only
10-20% of the time was usable for the survey. This is not enough as for some periods a daily
basis observation program is needed (during the emergence of the third south hemisphereband) for understanding what is happening more exactly.
3- Reference documents:
Please refer to the attachments:- The scope factor,- Uranus spectrum (from Mr Sromovsky),- Uranus results (.xls file), present opposition 2012-2013 and the 91 drawings,- F20 pictures (IL, Yellow, IR742), Jul.2012,- “Viewing Uranus dual tests”,- Necessary conditions for capturing features on Uranus with annexes,- Comparatif scopes-Uranus,- Uranus methane bands for visual CCD,
- GraphspectraKarkoschka,- Uranus resume 2010-2011.
Stanislas Maksymowicz
Ecquevilly- France,BAA member nƒ 32334
Uranus section.

Uranus on July 2012 SC305mm F20
Without filter

Yellow W12 filter

NIR 742 filter

Date
23.7.1224.7.1225.7.121.8.128.8.1210.8.1211.8.1217.8.1225.8.128.9.1215.9.1229.9.1212.10.12
15.10.12
22.10.12
23.10.12
27.10.12
1.11.122.11.124.11.12
15.11.12
21.11.12
25.11.12
29.11.12
2.12.128.12.12
11.12.12
17.12.12
30.12.12
1.1.1311.1.13
16.1.1317.1.1326.1.1330.01.13
14.02.13

Scope mm
DK180SC305
SC305
N200
N200
N200
DK180
SC203SC203
SC203
R150
SC305
Cass 235
Cass 235
MC150
SC305
SC305
SC305
SC305
SC305
SC305
SC305
Cass 235
Cass 235
SC305
Cass 235
SC305
SC280
Cass 235
SC280
SC280
Cass 235
SC280
SC280
Cass 235
SC280

Gx360/ 432
435/ 506
506
333/ 400
333/ 400333/ 400360333333
333
375
339
375
375
313
435
339/ 435
381
339/ 435
339
435
435
375
375
435
375
435/ 506
400
375
400
400
375
400
400
375
350

Heigth °
3942
3744
42
44
34
30
35
40
40
36
42
32
2539
42
42
42
28
32
39
34
40
36
40
42
41
39
36
40
34
35
36
34
27

CM °
1--91
117--193
203--258
260--344

Nights101259Nights
rate
DWGs

Seeing/10
8
78
7
7
76678
10656
9
7
665
6
7--8
6667101066668
76
56Transp./6556555565464
65545
6
6
4
4
65
54455455
544
66D equiv.
124
172
172
114
114
114
124
115
115
115
138
172
146
146
100
172
172
172
172
172
172
172
146
146
172
146
146
158
146
158
158
146
158
158
146
158

CM °
293/303
88/97
217/226
141/150
32/42
326/337
50/64
84/91
290/298
139/16446/63
203/215260/266
280/284160
340/344205/209193
332/336
185/189294/29678/81
254/258170
158/166
284/3081--10
121/124
180/192
117
61
62/64
175/182
16
222
179

Bands n°3
3
3
2 fuzzy
2 fuzzy
2 fuzzy
22 fuzzy
2 fuzzy2 fuzzy
333
2
2 fuzzy
332
3
3
3
4
3+1?
3
4
4
4
3
2
3
4
4
4
4
33+1?

Band south
Band equa.
Band northBrightenings
2
faintdiscret
2
2
faint
yes variations
3
2
faint
yes variations
4hemispherenot seenfuzzy darker
0hemispherevery faintfuzzy darker
0hemispherenot seenfuzzy darker
0hemispherevery faintfuzzy darker
0hemispherevery faintfuzzy darker
0hemispherevery faintfuzzy darker
0hemispherevery faintfuzzy darker
0
2
faint
fuzzy variations
2
2seen
yes variations
22
seen
yes
3
2 faintseen
yes darker
2hemispherevery faintfuzzy darker
0
2
seen
yes2?
2 fainterseen faintyes darker
0hemisphereseen faintyes darker
0
2 fainterseen faintyes darker
0
2 fainterseen
yes darker
0
2 variations
seen
yes less dark
13
seen
yes less dark
0
2+1?
seen
yes less dark
12
seen
yes less dark
03
seen
yes less dark
13
seen
yes less dark
13
seen
yes less dark
22seen
yes darker
2
1+hemisphere seen faintyes darker
1
2, 1 equa faint seen very faint yes less dark
13seen faintyes darker
13
seen faintyes less dark
2
3
seen
yes variations
2
3
seen
yes variations
32seenyes darker
22+1?
seen faintyes darker
0

July 12

AugustSept.12

Oct.12

Nov.12

Dec.12

310%
8

620%
19

310%
13

515%
9725%
15Jan.13
515%
15Feb.13
620%
11

13%
1

Location
limbs at equalimb equa near meridian
limb equa south meridian
N/A
N/A
N/A
N/A
N/A
N/A
N/A
limbs equa meridian
limbslimbs eaqua, south hemilimb, south hemi
N/A
between hemi bands south
N/A
N/A
N/A
N/A
limb rise equa
N/Aafter meridian equa
N/Alimb rise equalimb to meridian equalimbs to meridian equalimb set south, hemi riselimb setlimb set south, hemi rise
meridian equalimb rise, meridian hemi southlimb rise, limb hemi southlimbs equa, limb hemi southlimbs equa
N/ASouth clear polar regio
yes
yes dark collar
yes dark collar
yes with collaryes with collar
yes with collar
yes with collar
yes with collar
yes with collar
yes with collar
yes dark collar
yes collar fainteryes collar fainteryes collar fainternot seen
yes dark collar and clear band
yes collar fainteryes collar not seen
yes collar not seen
yes collar fainteryes collar fainteryes collar fainteryes collar darker
yes collar darker
yes dark collar variations
yes dark collar
yes dark collar also in blue co.
yes dark collar
yes dark collar
yes dark collar
yes dark collar variations
yes dark collar
yes dark collar
yes dak collar variations
yes dark collar
Yes dark collar

Necessary conditions for capturing features on Uranus.

1- Requested conditions:
Data are extracted from the publication“Observing the moon, planets and comets”
By Clark R. Chapman and Dale P. Cruikshank.
1.1- Uranus surface brightness (B)Albedo: 0.509
Surface brightness:
Saturn albedo: 0.461
Surface brightness:

54 cd/m2
180 cd/m2

Sky transparency: µ
Minimal visual sky transparency: usually m: 4.0 to 5.0 well accessible,
Filter in use (usually: W82A, W8, W12, W.F.): coefft.>0.80,Clean optics: coefft.>0.80 (including refelectivity and CO optical).
Britghtness through the telescope: B+ = D2.Bf / d2.M2 or 25.D2.µ.B / M2
D: aperture (here 8” or 200mm),
d: eye pupil diameter,
Bf: brightness at scope exit Bf = µ.Bm = 4.0 µ = 0.05 Tr (sky) 0.4 to 0.8
m = 5.0 µ = 0.25
B+ for D 8” M = 360x µ = 0.05 Bf = 2.5 cd/m2
d = 0.55mm or 0.022” µ = 0.25 Bf = 12.5 cd/m2
B+ = 0.15cd/m2 D 8” M 360x m: 5.0
B+ = 0.03 cd/m2 D 8” M 360x m: 4.0
Needed optimum magnification P = M/D (magnification per inch aperture) orSQR(25.µ.B/B+)
1.2- Optimal conditions:
For 8” aperture 360x magnification m:5.0:
Brightness at the eyepiece:0.15 cd/m2
Brightness of planet:
50 cd/m2
Requested magnification per inch: 45.6x therefore 365x for 8”
Mesopic vision:
Lighting level from 0.001 cd/m2 until 10 cd/m2
FOR A STANDARD EYE.
Observation of Uranus features mainly for 619nm area.
Represents about 40% of the max eye sensitivity for a mesopic vision
So the planet brightness at the eyepiece of 0.15 cd/m2 becomes 0.06 cd/m2.
The use of a W8 filter represents the ratio of the 40% under eye senvitivity curve.
0.06 cd/m2 level preserve well the mesopic vision abilities with the scope conditions notaffected.

1.3- Contrast perception:
a- Uranus exhibits clouds on a tiny 3.60” disk size.
Width of the cloud bands, say: about 1.0”
1.0” x 360 (magnification) = 360” or 6’ arc apparent size at eyepiece,
Therefore 10 cycles/ °,The standard eye contrast sensitivity function at 10 cycles/°:- mesopic vision: 1-2%
- photopic vision: 0.6-0.7%
for the planet on subject.
b- Scope effect:- Strehl ratio:
contrast through scope = actual contrast of feature x strehl ratio
Strehl 99% not affecting results.
c- CO, central obstruction:
For a RC200 with CO 35 and 42%, resolution limit remains 0.60”,
FTM curves exhibit the fact that contrast are kept in comparison with a perfect scope ofno CO near the ultimate resolution ability (right part of the curve).
d- Maximisation of the magnification for the contrast perception at low light levels
should be at about 10 cd/m2,
but performance (contrast versus feature size) can be kept with the proper increased
magnification.
8” scope with 400x
M: 5.0, clean optics, µ: 0.25
Seeing good to excellent (Danjon scale 10/10 to 7-8/10),
Contrast through the 8” scope
For features as lines: c+ = c.(w/(w+5.6/D))
w: line widthc: actual feature contrast
c+: observed contrast
for 1.0” width line, c = 1%,
for 1.2” width line, c = 1%,c+ = 0.59%
c+ = 0.63%

for a 12” scope and c = 1%
for a 16” scope and c = 1%
for a 40” scope and c = 1%c+ = 0.68%
c+ = 0.74%
c+ = 0.88%

e- Optimum observational conditions including the seeing for contrast perception:- 10” scope perfect, µ 0.1, m 4.5, M 540x seeing 1/3” (Danjon 7-8/10),
M 280x seeing 1” (Danjon 3-4/10),- 16” scope perfect, µ 0.1, m 4.5, M 710x seeing 1/3” (Danjon 7-8/10),
M 325x seeing 1” (Danjon 3/10),- 8” scope, 360x seeing <1/3” (Danjon 9-10/10)
Apparent size at the eyepiece about 22’ arc, surface apparent brightness 0.15-0.20 cd/m2
The contrast perception can be 1.50%.

- 8” scope, 400x seeing < 1/3”,
Apparent size 24’ arc: the contrast perception can 1.30%.
2- Tests performed:
2.1- Distanced targets:
Creation of targets.
Software word can ceate features until 5% contrast level.
Disk size at 1000m distance: 17mm
a- Background color of the disk: light grey (10% contrast with a whitish paper)b- Feature levelled at 15%See the specimen.
c- Same specimen with 2-3% contrast level.
d- Lighting conditions of the target:
Day light with no sun,Twiglight,
Moon light (full moon as 0.5-1.0 Lux lighting).
e- Seeing evaluation:
An artificial star was installed just near the target panel.
Worked well in twilight and moon light.
f- Results:

L110
L150
RC200Seeing

C=5%
Y.Y.Y Y.Y.N
Y.Y.Y Y.Y.Y
Y.Y.Y Y.Y.Y
10/10 7-8/10

C=2-3%
Y.Y.N Y.(Y).(N)Y.Y.Y Y.Y.(Y)Y.Y.Y Y.Y.Y
10/10 7-8/10

M308x
313_350x
360x
Sapochromat
achromat
Ritchey

Results were aleatory when S < 7/10 continuous.
Answers formatted as: Y.Y.N (daylight, twilight, moon light), Y: yes pass, N: not pass.
2.2- Personnal eye evaluation:
Performed at a famous Engineering Body for oil and gas activities.
Divers can be tested under US standards.
The tests were conducted in B G R colors, low light levels, FTM grids for some.
Results:
50” resolution ability at few lux illumination of examined targets of very low contrast
levels (<5%).
3- Works performed:
3.1- Observations since the 2009 opposition,
Results published at the Japanese Alpo and the BAA Uranus section
http://alpo-j.asahikawa-med.ac.jp/Latest/Uranus.htm
The results shows some variabilities of the planet (especially last opposition 2010-2011)- slight contrast variabilities,- cloud activity accessible in visual fields.
3.2- Uranus requested conditions:

The spectrum of Uranus exhibits absorption rays in visual area (especially at the 619nm),
but other lighter rays are existing in other visual fields.
Rather than the direct visual observations, some US amateur observers (Schmude, Mellilo,…) suggested the follow-up of the activity of Uranus though the collection of spectrum(absorption rays variation).
Some polarimetric observations for investigation should be undertaken also, being a notnegligeable parameter at priori (having owned a C8 with a light polarimetric effect, that
may false some data).
Think that the features collection remains accessible directly visually but to-day at themargin of a 150-200mm scope aperture.
The pertinence of the result is:- lightly improved with the aperture increase, the seeing parameter becoming the moreinfluent parameter quickly,- at the best when the global transparency and transmission are at the best possible,- at the best when the scope strehl ratio is high (>95% actual and global),- at the best when the exit pupil diameter is fixed to 0.50-0.55mm, where the mesopic
vision potential is at the best conditions.
4- Conclusion:
The present study may involve a good pertinence and reliability of the given results by:- the respected best mesopic vision conditions,- the results get on distanced targets,- the personnal vision control.
If visual observations are faced to difficult conditions, what is sure is- average trained observers cannot do something fruitfully,- imagers are also faced by these observational conditions, features being washedquickly by the site observation condition and the lack of scope quality (as apreliminary approach).
Stanislas Maksymowicz
BAA member
Uranus observer.
Annexes:- article from www.telescope-optics.net/eye_spectral_response.htm,- fig.1 from the Chapman and Cruikshank publication- tablesheet from the Chapman and Cruikshank publication, sheet 182-183,- table 2 from the Chapman and Cruikshank publication, sheet 145,
- table 3 from the Chapman and Cruikshank publication, sheet 146,
- table 4 from the Chapman and Cruikshank publication, sheet 152.

Y axis: disk size in (‘) arc
X axis: contrast image
Curves: for surface brightness image in cd/m2

Newton 203mm CO29% L/4

Refractor 150mm L/6.5

Cassegrain 200mm CO40% L/8

MEWLON 180mm CO30% L/10

Cassegrain 305mm CO33% L/4.5

Cassegrain 305mm CO33% L/4.5

84 drawings (26nights) were performed this present opposition with200-305mm apertures (July 2010-February 2011).
Uranus exhibited from the August 2010 to February 2011 period
some variability accessible visually with the aid of light coloredfilters.
Almost featureless at the beginning where EZ was only accessible
to be captured, then more consistently brighter in yellow-near IR
spectra portion on September in EZ and fading and diluting in a
bubbling system at the end of December.
On January 2011, EZ seemed to reconstitute but faintly.
Clear bright patches appear brighter at planet edges than at themeridian.

2010.01.30th 2010.08.28th 2010.09.17th 2010.09.18th 2011.01.16th
MC:298Ä

MC:194Ä

MC:83Ä

MC:238ÄCassegrain 305mm x381-435, filter W8, S:5-7/10, T:6/6.

Stanislas Maksymowicz
Ecquevilly- France (JN08XW)
BAA member nÄ 32334
Uranus section.

MC:168Ä