AAVSO: American Association of Variable Star Observers

Proposal #324

Proposer (45204) Krzysztof Zieliński (krzysztof.s.zielinski@gmail.com) obscode: ZKRA
Assigned To(3663) Dirk Terrell
Date SubmittedMarch 26, 2023

DF Cyg
SY Dra

Requested filters:
B, V, R, I

Exposure times:
The longest possible. Initially, I would request 3 images in B band, 2 in V band, 2 in R band and 1 in I band to be taken per run (per target). B, V, R images would be later stacked in order to achieve better SNR.

Observations start date:
As soon as possible.

Expiration date (DD-MM-YYYY):

Desired frequency of observations:
DF Cyg: Daily
SY Dra: Weekly

DF Cyg:
I have been observing this RVB-type variable star since June 2022. However, my cadence of one observation per week (on average) is insufficient for a star with a period of 50.08 days (VSX). There are a few other observers and their observations, but if we were to plot a light curve of, say, the last 200 days, we would see that the data points are sparsely located. My idea is to create a detailed light curve using CCD photometry that will be supported by visual observations. Perhaps not only would we see more clearly the changes in the star's brightness, but also, through the use of different filters, the changes in B-V (and other relations) over time. As far as I know, this has never been done before for this object on a longer time scale. About a week before submitting this proposal, through CHET, I requested brightnesses of the comparison stars in the field to be determined. Several stars in the range from about 10.2 mag to about 14.5 currently have their magnitudes determined in the B, V, R, I bands with an overall error of 0.04 mag. I highly recommend allocating DF Cyg to BSM-TX if the proposal is accepted. This project is also a fruit of personal curiosity. The star ranges from about 10.0 mag to about 13.5 in V.

SY Dra:
SY Dra is currently imaged in B, V, R, I filters once a week by BSM-TX and BSM-NM (Proposal #300 - SY Dra, V Dra, Z Cep). However, the original proposal expires on 01-04-2023. I would like AAVSOnet to continue its observations. BSM-TX is recommended. It is a Mira-type star that has currently about 13.8 mag in the V-band.

All data would be submitted to AAVSO database after VPhot analysis.

Krzysztof Zieliński (ZKRA)

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
SY Dra 17.566050 53.96044 14.0–10.5 BSM_TX 5 Oct. 1, 2023 No
DF Cyg 19.814980 43.03739 13.88–10.12 BSM_TX 1 Oct. 1, 2023 No


(4726) Kenneth Menzies — March 31, 2023, 6:13 p.m.

Why not just add DF Cyg to your existing proposal 300 on TX and NM? Easier for all?

(4726) Kenneth Menzies — March 31, 2023, 6:28 p.m.

Submitted to TX and NM on Proposal 300.

(45204) Krzysztof Zieliński — April 10, 2023, 4:41 p.m.

I recently received the first images. However, not only images of DF Cyg and SY Dra, but also V Dra were sent to me. I did not expect V Dra to be observed by AAVSOnet anymore (since the original proposal expired 01-04-2023).
1. Is this a misunderstanding? If not, I would like to point out that V Dra and Z Cep are no longer difficult for me to observe visually and therefore I have no need for AAVSOnet support. Moreover, there are other stars in my visual program that would be much more valuable to image. Also, DF Cyg currently has the highest priority for me and I would want it to be observed whenever possible. Removing V Dra and Z Cep from the queue would free up some valuable time.
2. Secondly, I received 2 images in the B band, 2 in V, 2 in Rc and 2 in Ic, although I asked for 3 in B, 2 in V, 2 in Rc and 1 in Ic. This was due to my previous experience, as the SNR of the imaged target stars was always relatively very high in the Ic band compared to the one in B or V band (which is actually nothing extraordinary for Mira-type stars).

Krzysztof Zieliński

(4726) Kenneth Menzies — April 15, 2023, 3:22 p.m.

V Dra and Z Cep removed. DF Cyg already has a cadence of 1 day as requested earlier.
What SNR are you getting with each exposure?

(45204) Krzysztof Zieliński — April 15, 2023, 7:34 p.m.

Listed below are the SNRs of DF Cyg in B, V, R, I bands from the two nights (from single, unstacked images). Aperture = 9 pixels.

2023-04-07 (BSM_NM2), ~11.8 mag in V:
~80 SNR in B (300s)
~240 SNR in V (240s)
~330 SNR in R (175s)
~250 SNR in I (150s)

2023-04-12 (BSM_NM2), ~11.5 mag in V:
~210 SNR in B (300s)
~400 SNR in V (240s)
~480 SNR in R (175s)
~300 SNR in I (150s)

Comments on this proposal are closed.