UT Mar 25, 2024: Photometry of SZ Lyn

Michael Richmond
Mar 28, 2024

On the night of Mar 24/25, 2024, under good conditions, RIT students Myrra Small, Karina Bryant and I acquired images of the delta Scuti variable star SZ Lyn. They are part of the PHYS 373 "Observational Astronomy" class, and their project is to make a light curve of the star.

We acquired images in B and V passbands, getting roughly one full period through both filters. I also reset the polar alignment of the telescope, so that it will now point at objects properly.

SZ Lyn

This pulsing variable star has a very short period of about three hours, with an amplitude of roughly 0.3 mag in V-band. It's a pretty easy target at ninth magnitude.

These observations involved:

• Meade 12-inch telescope
• no focal reducer, so working at f/10
• ASI 6200MM CMOS camera
• B-filter 30-sec, V-filter 10-sec images
• images binned 4x4
• no guiding
• focus position on 12-inch:
  • in V, initially 0.312 yields FWHM 5.0 at T = 30/0 ish ?
  • in V, after removing camera/replacing camera: 0.233 yields FWHM 4.0 at T = 30/0 ish ?

Notes from the night:

• mostly clear at sunset, but light clouds came and went throughout the night
• bright nearly full Moon
• camera at T = -20 C
• telescope did not understand where it was at the start of the night -- a problem which had been occuring for several weeks. After spending too much time trying to star-hop to SZ Lyn, we bit the bullet, removed the camera and all cables, and re-ran the polar alignment procedure. Afterwards, it was able to move to an object properly.
• no animals :-(

The picture below shows an image of the field of SZ Lyn from this evening. The field of view is about 22 arcminutes across.

I've marked the location of several comparison stars.

  star       name                  B          V         
------------------------------------------------------
    A     APASS 6365302        12.154     11.327 
    B     APASS 6365252        11.850     11.391 
--------------------------------------------------------------------------

 

Here's the sky background over the course of the run:

The FWHM:

The graph below shows changes in the photometric zeropoint of an ensemble solution of the imstrumental magnitudes over the course of the run.