Late spring/early summer CV target suggestions

Hi folks,

Here are some more targets to consider working as we move through spring towards summer.

V1674 Her – AKA Nova Herculis 2021 – This is an Intermediate Polar that went nova and has been very heavily studied since it went off in November of 2021. It has been the subject of multiple papers like this one.

It has an ~8 minute white dwarf spin rate that shows up easily with time series of 2 minute exposures in 12" telescopes despite the system running around 18th magnitude. A signal to noise of 10 to 15 gets the job done. The orbital period is about 3h and 40m so long runs and runs from multiple observers across longitudes are most valuable.

DQ Her – The prototypical Intermdiate Polar with a white dwarf spin period of 71s. Cadence of 30s or faster can show the white dwarf spin and help track the evolution of this system.

U Sco – A morning object. See Brad Schaeffer’s comments here:

Two opportunities with U Sco. Coverage out of eclipse and coverage during the eclipse to allow eclipse timing. Both are important to figuring out how recurring novae like this work. The eclipses go pretty deep – about 19.5. Gordon Myers has been covering the eclipses with a 17" scope in Australia. More help definitely needed. The data for the eclipse timing has a lot of noise and so more eclipse runs are a big help.

For out-of-eclipse data points, you’ll want to stack several exposures to get good S/N for U Sco at about 18th mag. Peter Nelson has been doing most of the out-of-eclipse photometry for the last several years. Plenty of opportunity to help him out. You can use VSX to get an ephemeris for when U Sco is eclipsing to make sure you are out of eclipse.

Other targets to consider:

Early evening objects:
AM CVn
VZ Sex – no time series yet this year
CR Boo – no time series yet this year

After midnight targets that would be good to get early season runs on include
V Sge
V1974 Cyg
V1500 Cyg

Other targets people might suggest?

Clearest skies,
Walt

Hi Walt,
please also give targets in the Southern Hemisphere.
Thank you,
Josch

Hi Josch. What would you think about this system? IGR J16167-4957 = 1RXS J161637.2-495847. Here is the link to Koji’s IP catalog for it.

Not lots of optical work on it in the literature. Can you find a spin period for it? Long runs would be good to get another read on the orbital period of approximately 5 hours, but I think generally your preference is for short runs on multiple objects vs. long runs on one object.

Clearest skies,
Walt

Josch, U Sco is better placed for you to do photometry of the eclipses from Chile than it is for folks in the northern hemisphere. Is that one you could work? Gordon Myers has been very successful working it from Australia and is about the only person getting photometry through the eclipse. Brad Schaefer showed some data a couple of years ago illustrating how difficult it is to get good enough TOM accuracy to follow the evolution of U Sco. Lots of time series each season were essential to beat down the noise.

-Walt