GSSP - Lassen Peak parking lot (1/3)

by Alvin Huey

NELM was 7.5 or 7.6 at best as I discussed in an earlier post.

First part will contain Hickson Groups. Second will have the Abell Galaxy Clusters and last, everything else. Sorry, I don't have long stretches of time to write as I'm quite busy right now.

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My goal in the following observations is to take advantage of these nice Lassen skies and detect members not previously detected in the past. So far, I was able to fish out 7 additional members in 6 Hickson Groups.

All observations were with the 22" f/4.1 reflector using the 7mm, 5mm and/or 4mm TMB Supermonocentric eyepiece. No Paracorr.

Hickson 72 (458x)
In addition to Components A to D previously detected.
-Component F (PGC 52849, 18.3, 0.2x0.1') pops in and out as an extremely faint and extremely small round patch. Almost stellar in appearance.
-Component E (UGC 9532, 0.3x0.2', 18.3) was not detected, probably because it is more spread out.

Hickson 73 (327 and 458x)
Components A to C previously detected.
-Component E (PGC 53702, 0.2x0.1', 17.5) is detected as a very small and very faint round patch. A star lies about 2/3 of the way between Components E and A (NGC 5829)

Hickson 75 (458x)
Components A to E previously detected.
-Component F (PGC 54802, 0.2', 17) pops in and out and stellar in appearance.

Hickson 76 (327 and 458x)
Components A to D previously detected.
-Component E (PGC 55325, 0.2', 17) - nearly stellar patch held steady with averted vision. It lies about 1' west of Component A.
-Component F (PGC 55313, 0.2' 16.8) - nearly stellar patch held pretty well with averted vision. It is very close to the relatively bright Component B (MCG+1-40-3, 0.4x0.3', 14.9) and sometimes lost in the glare. It could not be detected at 327x.

Hickson 78 (458x)
Components A, B and D previously detected.
-Component C (PGC 56095, 0.5x0.1', 18.1) - Thin even surface brightness streak held about 75% of the time with averted vision. No brightening of the center detected. PA = 170.

Hickson 98 (573x)
Components A to C previously detected.
-Component D (MCG+0-60-60, 0.3x0.2', 17.5) - almost stellar. Held most of the time with averted vision. There is an obnoxiously bright mag 10.1 star sitting 1.1' north. The key to detection is to keep it off the field, so I used the 4mm Supermonocentric eyepiece giving 573x with a little 3.1' field. Tracking was a little tough, but fortunately I was able to find a way for the field to drift without letting the star pop into the field.

The 6" f/6.5 achromatic refractor from Antares is a pretty sweet and well corrected refractor. Shows less color than the Celestron/Synta 6" f/8 refractors. Star test is very very good, very slightly under corrected. Closest double resolved with this little scope is 0.9", barely resolved though. I have this thing mounted on an Orion SVP mount, which is suitable for visual use.

Anyways, I decided to observe Stephan's Quintet, Hickson 92.

Hickson 92 (Stephan's Quintet)
6" f/6.5 achromatic refractor at 198x

Using the 5mm TMB Supermonocentric eyepiece, I was able to detect 4 separate clumps arranged like a "T".
-Component A (NGC 7320, 2.3x1.1', 13.2b) was a faint 2:1 even surface brightness patch with diffuse edges. No central brightening detected. PA = 135.
-Components B and D (NGC 7318A/B, 1.4x0.9' and 0.8x0.8', 13.9b and 14.3b) was detected as a faint even surface brightness 3:2 elongated patch. I did not detect the two distinct nuclei, so this pair remains unresolved. PA = 60
-Component C (NGC 7319, 1.3x0.8', 13.1v) was a very faint even surface brightness round patch.
-Component E (NGC 7317, 0.8x0.7', 13.6v) was a faint and small round patch with a slightly brighter center.

I felt that component E showed the highest surface brightness of the five members, probably due to the brighter center.

I tried for NGC 7320C (0.6x0.5', 16.7b), which lies 4' east of NGC 7319, but did not detect it.

Clear dark skies,

Alvin