Monday, November 21, 2005

Central Park Observing - 20 Nov. 2005

Location: TotL - Central Park's Great Lawn (north end)
Date/time: Sun., 20 November 2005 (6:05p-8:15p)
Optics: 10x70 Fujinon's (mounted), Tele Vue-76
Conditions: winds var.-SW from 5-9 m.p.h., temp. 53°F

Another evening dedicated to the hunt. The search area is SALC 34N in Perseus which includes α, ι, κ and δ Persei.

Conditions were clear, cool with a south-west wind blowing on my back. Tonight was the first night working with a Cartes du Ciel (CdC) chart printed with asterism lines.

Transparency improved as the session progressed. The binocular limiting magnitude (BLM) was 9.2 early on increasing to 9.3+ towards the middle of the session. Start time was 6:05p. The full area was covered in 1.5 hours ending around 7:35p.

This is quickest I've been able to cover all of SALC 34N. I don't think it can get much quicker if I'm going to thoroughly check out the starless regions for potential novae. Having a chart with a limiting magnitude of 9.5 helps eliminate the time spent triangulating and plotting stars that aren't on the chart.

Ken was setup at the top of the lawn showing Venus to a small crowd through a spotting scope. Tom C. showed up a bit later. Both left early on.


Variable Stars:

V410 Persei was seen for the first time tonight. It was the dimmest star in the area surrounding the ‘Three Boxes’ asterism making it ~9.2. V410 Per is a semiregular variable with a late-type spectrum (M, C, S or Me, Ce, Se). The quoted range is between 8.8 and 9.4. The period is listed as 110 days. This star should be visible in the 10x70's, even at its dimmest, on most evenings.

Here is a description of an SRB variable star from the General Catalog of Variable Stars (GCVS):

Semiregular late-type (M, C, S or Me, Ce, Se) giants with poorly defined periodicity (mean cycles in the range of 20 to 2300 days) or with alternating intervals of periodic and slow irregular changes, and even with light constancy intervals (RR CrB, AF Cyg). Every star of this type may usually be assigned a certain mean period (cycle), which is the value given in the Catalogue. In a number of cases, the simultaneous presence of two or more periods of light variation is observed.

The chart's limiting magnitude is 9.5 which goes just beyond the limiting magnitude of the Fujinon 10x70's in Central Park. BLM for the evening was 9.2 - 9.4.

Number of stars seen: 419. Area covered: 5 degrees of declination by 50 minutes of right ascension.


Tag said...

I see you brought the TV76. Did you set up and have some looks?

Perhaps when the crowd is thin, you get more done in a shorter amount of time :^D


Ben C. said...


I went to the park with three purposes in mind:

• Scan SALC34N
• Find out how &145;easy&145; it would be to wheel along the ‘observatory’ with the binoculars.
• And to take a look at the field of Nova Persei 1901

All were accomplished and found I need to work on a way to handle the eyepieces. Bringing them in their orig. boxes isn't working out. I also brought the prism diagonal but prefer the star diagonal on the night sky. The prism diag. works very well on daytime objects.