TASV J1835+383 - GSC 3105.1376

(Q1996/010-Q2000/003)

A suspected variable comparison star for LL Lyr.

In 1996, Eric Broens (Director of the Belgian VVS) reported to Guy Hurst (editor of "The Astronomer" magazine)  that the 136 comparison star shown SE of the UG star LL Lyr on the AAVSO chart looked fainter than its listed magnitude, and estimated it to be mv=14.1. This query was assigned as Q1996/010 by Hurst.  Following this, Guy Hurst identified the star as a suspect variable on both paper and FINDERS TA charts referenced 960219.

Independently to this I came across an AAVSO chart for LL Lyr in my filing cabinet, and began observing it in the Spring of 1997. Some months later it became apparent that the 136 comparison star mentioned above seemed to be showing variations. I began to monitor this field star closely, and the resulting observations have lead to the light curve shown below. Upon informing Guy Hurst about the suspect nature of this star (my querey was then referenced as Q2000/003), he informed me of the earlier report made by Broens, whom I then contacted to inform him of my observations and to see what data he had. Unfortunately he had only made that single observation of the star in 1996, and failed to undertake any long term monitoring. This was somewhat of a disappointment to me, as a second observers observations over a longer time period would obviously have produced a more detailed light curve.  

Following a write up in TA magazine Vol 36, No. 431 p284 the suspect was given a TASV designation in July 2000.

Details of the suspect comparison star are...

GSC 3105.1376

RA 18h 35m 20.191s

Dec +38d 18’ 31.96 (2000.0)

Magnitude 14.19 +/- 0.42

(From GUIDE 7)

The star lies 1.9’ SE of LL Lyr at PA 118.6d

The AAVSO chart (dated 5/27/80) records the star with a designated magnitude of 13.6 (see below)

The light curve is produced from just 82 visual observations made between April 6th 1998 & December 12th 1999. Checks were made at intervals of five days or greater - despite LL Lyr being checked nightly for outbursts -as it was immediately apparent that the light variations were not of an eruptive nature. An amplitude of 0.9 magnitude (13.7-14.6) has been observed over this period, but long term monitoring is required to establish any regularity (or semi-regularity) in the variations.

Click HERE for a monthly updated light curve for GSC 3105.1376

Observers of LL Lyr using the AAVSO sequence should be aware that GSC 3105.1376 is not suitable for making estimates when LL Lyr is in outburst, and should be avoided at all costs. It is also hoped that observers who regularly monitor this dwarf nova will also endeavour to estimate the brightness of this field star, and report it to the AAVSO, TA/BAAVSS in the hope that  we can establish it’s true nature.

Gary Poyner  (March 2000)

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