Proposal #219

Dear Sir / Madam ,
This is for your kind information I am an AAVSO member since 2018 and this year I have been selected as an AAVSO AMBASSADOR from India.
I would like study the long-term period change analysis of the Cepheid (DECP) “ TY Sct ” using O-C method after doing the photometry using VPhot.
For this purpose I am requesting you to get CCD images ( .fits or .fit format ) using the facility of AAVSO observing campaign ( AAVSONet scopes ) .
The necessary information related to this study are as follows.
Hope you will guide me in this regard.
With regards,
Pradip Karmakar

Name : Pradip Karmakar

Institution of reseacher :

Department of Mathematics, Madhyamgram High School (H.S.), Madhyamgram, Sodepur Road, Kolkata 700129, India.

Email id (researcher) : pradipkarmakar39@gmail.com

Target's Information:

The celestial coordinates (J2000.0) with respect to VSX (International Variable Star Index; https://www.aavso.org/vsx) of the target star and
other required information are as follows:

Target name: TY Sct

RA: 18 42 07.92 ( RA J2000 (deg) : 280.53274 )

DEC: -04 17 36.6 ( DEC J2000 (deg) : -4.29333 )

Variability type: DCEP

Spectral type: F7-G5

V Mag. Range: 10.31-11.25

Period: 11.05302 days

Purpose of campaign: I would like to study the present period change behaviour of this cepheid using the recent and the previous ( available in AID ( AAVSO International Database )and ASAS-SN Sky portal) data sets. My main target is to study the long-term period change analysis of this object using O-C method after doing the photometry of the CCD images ( .fit or .fits format ) using Vphot. At present I have no observing facility, so I would like to get support from AAVSOnet.

Background: After reading a paper of Emilia P Belserene (1989JAVSO..18...55B) I have been interested about this Classical Cepheid. 10 values of obseved “ Time of Maximum “ obtained by Christian Baily, were used in this paper by Emilia P Belserene. I made a search in AAVSO International Database (AID) about this cepheid. As per the record of AID, first observations were done in 1959 Aug.10.34500 CCD observations were recorded using U, B, V bands. After 16 years Visual observations were recoded started from 1975 Jun.07.40000 upto 2005 Aug.13.40000. After 3 years again CCD observations were recorded using V band, that is in 2008 Jun.01.39790. The last CCD observationonal records was on 2010 Aug.13.44470. After that two Visual photometry records are there (2011 Aug. 30.86000 and 2016 Jul. 24.21197 ). So, I would like to continue the period change study of this star. Although I have some CCD photometric results of this star in ASAS-SN Sky portal from 2015-01-30 to 21-06-27. Only one observation result on 2021-04-22 in V-band. From 2015 to 2018 the results are mostly based on V-band and from late 2018 to 2021-06-27 are in g-band mostly.
Duration of campaign: As I am not well experienced so it is quite hard for me to comment about what should be the suitable cadence. The period of this star is 11.05302 days, so I would like accept which is better for the cadence as per AAVSOnet observation committee. As it is a classical cepheid, so it is better for long term observation should be better for better understanding about this cepheid. As per the recod in AAVSO-WebObs genrally the cadence are around 24 hours. Maybe I am not absolutely correct. But as per ASAS-SN Sky portal observational records, there are different cadence have been used. The duration of the campaign may be four months (from July-2021 to October-2021).
CCD observations: Yes, I would like to avail CCD coverage.
DSLR observations: No. I would not like to avail DSLR coberage with BGR filters.
Visual observations: No. I would not like to avail visual observation coberage.
Filters: I would like to avail CCD observations using V, B, Rc, and Ic (if possible).

Comparison and Check stars: I would like to get help about the sequence for this target from the Sequence Team.
Submitting observations: I would like to get the images ( bias and dark corrected and flat filded) in my VPhot account,
so that I can do the photometry of those images (.fits OR .fit format) using VPhot. I am very much eager to use VPhot
for the photometric measurement.