Short Period Pulsators (SPP)

I was trying to use the SPP RR Lyrae Ephemeris of plan an imaging session.  I can't see how the predicted "time of maximum" lines up with the ephemeris you get from VSX.

For example, I was considering RR Gem for tonight.  Here is what the SPP ephemeris says for the days around tonight (Feb 5th in local time)

4-5     7.0

5-6     2.0

6-7     6.5

I would think I would use the 5-6 line and in my time zone (-7 UTC), that would be 7 PM on the 5th.

However, if I look at the VSX ephemeris, I see:

2459980.345   04 Feb 2023 20:16

I've tried to use the Period-Luminosity relation formula which I found on " https://de.wikipedia.org/wiki/Perioden-Leuchtkraft-Beziehung " but it seems to be quite unaccurate. Do you have some other more precise way to calculate the absolute magnitude of a Delta Scuti variable?

I'm working on a school project and I have to determine periods of different types of variable stars in order to calculate the distance. For this reason I am looking for images of different variables stars like Cepheids and eclipsing binaries. A data set with at least two visible visible peaks is needed and the more images you have the better! All kind of Cepheids are welcome, stars like RR-Lyrae-type, Mira-type, long period/short period, delta-scuti-stars.

I'm really thankful for any data set you are able to provide.
Thanks,
Pavithiran

For those of you who are familiar with AstroImageJ (AIJ), a capability has been added to the latest daily build that allows the user to create a variable star report that conforms with the AAVSO International Database (AID) format for both single comparison stars, as well as for an ensemble of comparison stars. I want to thank Ken Menzies and others who have helped with the testing.

AAVSO Alert Notice 786 announces an observing campaign on the RR Lyr star V338 Boo. Please see the notice for details and observing instructions.

There are threads for this campaign under the following forums:

- Campaigns and Observing Reports: https://www.aavso.org/v-338-boo-campaign-2022
- Short Period Pulsators (SPP): https://www.aavso.org/v-338-boo-campaign-2022-01

I'm not sure whether this is the correct forum for this question, but Eps Cep is a SPP (a Delta Scuti), so here goes... please note that I am new to photometry and am just trying to practice on some well-known variables, the eventual goal being to study exoplanet transits.

I see in the June newsletter about the SPP section: "Gathering observations in M13, as well as the “Legacy Stars,” so lots of data is expected to be collected over the next few months."  I've not heard anything about this but might be interested in contributing.  Are there more details to be had?

Richard

AAVSO Alert Notice 777 announces an observing campaign beginning immediately on the delta Sct variable EH Lib. Observations are critical now through at least the night of June 09/10. Please see the notice for details and instructions.

There are threads for this campaign under the following forums:

Following Dr Riess's suggestion in Saturday's webinar that a valuable contribution amateurs can make to the improvement of the Hubble 'constant' and the expansion rate/change of the universe would be to observe long period Cepheids I did a search in the fabulous VSX for DCEP with periods > 5d (and located north of -20d as I live in southern Canada, and south of +55 for the trees along my northern 'horizon') and I find that most of the stars are quite bright.

Hi,

What is the correct mathematical or physically method of determining the maximum of Delta-Scuti-Stars or HADS?

If I take the wohle lightcurve I get other results as I only take half of the lightcurve. Some collegues told me, only to take half of the LC, but is that only an opinion, or is there a physically proof somewhere?

• Does one take the whole LC, from the plateou (blue lines)?
• Does one take the whole LC, but only from ascent to descent?
• Does one take oly half of the LC (green line)

Bernhard