31 March 2007

Observing Location	VP
Observational Period	1000-1015 EDT
Atmospheric Conditions	Cloud Cover Overcast Temperature 47°F Wind Light Breeze Humidity Low Feels Like Pleasant It was very hazy with stripes of thicker cloud. Through the filter I could see a ring of illuminated cloud with an aparant thickness of .25-.5” around the sun. Transparency Poor Seeing I
Instruments	Brunton 8x21 compact binocular w/Welco gold shade 14 welder's filter - Charlie
Observing Party	Charlie Ridgway

Target Sunspots Constellation Psc Category Solar Time yyyymmdd.hhmm 20070331.1000 EDT Comments Distance Light Time 0.9 AU 8ms Angular Size 32'" Altitude ° Heliographic Latitude (B0) -6.59° Heliographic Longitude (L0) 358.68° Position Angle (P) -26.12° Carrington rotation number (CR) 2055 Group 949 is still there, but still two small for me to see. On the large SOHO image it looks like there might be two tiny spots there.   Groups Spots R North 0 0 0 South 0 0 0 Total 0 0 0 R = (Groups * 10) + Spots)

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Observing Location	TotL
Observational Period	2100-0030 EDT
Atmospheric Conditions	Cloud Cover Scattered Clouds Temperature 50s F Wind Calm Humidity Moderate Feels Like Cool We have been on the edge of a front passing NW to SE all day today. Sometimes we are in clear air and sometimes a bump of cloud will pass over us. Mostly the front is crossing Manhattan downtown to midtown. Lumps of cloud occasionally pass in front of Saturn and the Moon. The density of the clouds increased through the night. Transparency Fair Seeing II
Instruments	SAR: Coulter CT-100 Newtonian reflector - Charlie CelEDTron Omni 20mm CelEDTron Omni 2x Barlow ~20mm Lekkner w/helical focuser
Observing Party	Charlie Ridgway

Hawaiian George arrived shortly after I got set up and after we observed a bit we spent the rest of the evening comparing international travel notes until Times Up came through with about a dozen riders.

Target Saturn Constellation Leo Category Planet Time yyyymmdd.hhmm 20070331.2130 EDT Comments Object Class Classical Planet Elongation ° Distance Light Time (from Earth) AU hm Distance (from Sun) Au Angular Size "x" Ring Angular Size "x" Ring Inclination ° Magnitude 0.21 Altitude 65°41’ I could make out separation between the planet and the rings and Titan, but nothing more.

Target Moon Constellation Leo Category Lunar Time yyyymmdd.hhmm 20070331.2145 EDT Comments Lunation 1042 Phase Waxing Gibbous Age 12.00 Distance Light Time (from earth) 401,181 km s Elongation ° % Illuminated 97.5% Magnitude -1262 Angular Size 29.29' Altitude 39°41’ The moon looks nearly full to the naked eye but there is obvious texture on the western limb in the scope. I have found that, because of the date format I have chosen for Windows Vista, Starry Night is displaying the date in numerals in the format dd mm yyyy. So all of the recent statistics I have pulled from it are likely to have been in error as I was assuming it was mm dd yyyy and hadn’t noticed that it thinks the year is 2006 even though my computer knows it to be 2007.

I tried to get some information about the Kellner eyepiece tonight. I thought that if I did a drift test I might be able to back calculate to fighre out what its focal length is but that does not appear to be the case. I have not found any information in Astronomy Hacks on how to calculate the focal length of a lens if it is not printed on the lens barrel.

TFoV = T * 0.2507 * Cos(Dec)
T = 13:33 = 813 sec
Dec = 0°54’47”

Drift test using the Moon

TFoV = T * 0.2507 * Cos(Dec)
TFoV = 813 * 0.2507 * Cos(0.913056)
TFoV = 813 * 0.2507 * 0.611331
TFoV = 124.06008 acrseconds = 2.076681’

I tried four times to repeat the test using Vega and once with an unknown star in the south that disappeared into the clouds. I never got Vega to track across the full FoV. Astronomy Hacks has two solutions for this problem for Alt/Az-mounted scopes.

1. Do a half drift test. Place the target star in the center of the FoV, which they say any dummy can do - I guess I am not a dummy because I often place things in a different center of the FoV than Peter, and time it until it reaches the edge. When performing the calculations just double the time.
2. Do a half drift test to see where the star exits the FoV then back it off to the edge of the field 180° opposite and perform the full test.

I did some examination of the eyepiece and there is no indication anywhere as to who made it, what optical formula it is, or what its focal length is. There is a diopter scale that runs from +2 to -3 but no mark on the barrel to index it against.

I suspect that the eyepiece was bought as surplus and adapted for use with the Coulter CT-100. The lower portion of the lens barrel is 1.22” outside diameter and the loser extent of it is even narrower. There is a brass barrel extension that has been epoxied onto it that is 1.248” OD and 1.156” ID. The original tube is threaded at the bottom to accept a filter but the brass tube is not threaded. There is epoxy sticking out beyond the inner edge of the threads so you couldn’t even drop a filter down there and get it threaded on. The inner surface of the lower lens appears to be highly domed like a gum drop.

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Sunspots Observed

Observing Hours for the Year To Date

	Day			Night			Total
	Hours	Days	Avg	Hours	Days	Avg	Hours	Days	Avg
Jan	4.25	12	0.35	7.75	9	0.86	12.00	16	0.75
Feb	3.50	14	0.25	20.75	5	4.15	24.25	15	1.62
Mar	9.25	16	0.58	36.75	10	3.68	46.00	17	2.71
TOTAL	17.00	42	0.30	65.25	24	2.04	82.25	48	1.71