UT Apr 14, 2024: Photometry of AE UMa

Michael Richmond
Apr 17, 2024

On the night of Apr 13/14, 2024, under fair conditions, RIT students Ben Gebhardt, Quan Quy and I acquired images of the SX Phe variable star AE UMa. They are part of the PHYS 373 "Observational Astronomy" class, and their project is to measure the change in this star's brightness.

AE UMa

AE UMa is a short-period variable with a period of about 2 hours according to its entry in the GCVS.

These observations involved:

• Meade 12-inch telescope
• no focal reducer, so working at f/10
• ASI 6200MM CMOS camera
• B exptime 20 seconds, V exptime 10 seconds
• images binned 4x4
• no guiding
• focus position on 12-inch:
  • in V: 0.511 yields FWHM 4.0 at T = 50/10

Notes from the night:

• light clouds at sunset, clear for an hour or two, but then cirrus arrived around 11 PM, and forced us to close around 1:10 AM.
• almost first-quarter Moon high in southwest
• camera at T = -20 C
• temperature dropped from 50/10 at start of run to 39/4 when we quit at 1:11 AM

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

I've marked the location of several comparison stars from APASS9.

  star       RA       Dec          B          V         
------------------------------------------------------
    A    144.3689  +44.0213       12.370   11.383  
    B    144.2998  +43.9721       13.237   12.038  
    C    144.0877  +44.0298       13.194   12.552  
------------------------------------------------------

 

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 instrumental magnitudes over the course of the run.