Alert Notice 753: Monitoring requested for seven intermediate polars

August 23, 2021

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports: https://www.aavso.org/intermediate-polars-campaign
- Cataclysmic variables: https://www.aavso.org/intermediate-polars-campaign-01

Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomers and by HQ. Join in the discussion or ask questions there!

Ava Covington (University of Nevada, Reno) and Dr. Aarran Shaw (University of Nevada, Reno) have requested AAVSO observers' assistance in monitoring seven intermediate polar cataclysmic variables over the next year.

Covington writes: "We are observing these objects to obtain better coverage of them over sufficient timescales for several reasons. Nightly coverage will allow us to monitor these systems to see if they are entering a “low state” (drastic decrease in optical flux that lasts from weeks to years, ~0.5+ magnitude). Catching them when entering/during a low state will allow us to trigger programs on Chandra and XMM-Newton to observe the X-ray emission to better understand properties of the white dwarf. Additionally, AAVSO observations of these objects will allow us to analyze temporal signatures, with which we will build a picture of the dominant accretion mechanisms in the system that are causing the dips in magnitude."

This campaign begins now and will continue through August 23, 2022, with the possibility of extending it.

Photometry (V, CV) of the targets in the table below is requested. DSLR green and visual observations are welcome to supplement the light curves. The cadence requested is every other night, as weather permits, and "about one hour of coverage per night (enough to catch a few spin cycles of the white dwarf). If a source is found to be in a low state, then we request longer coverage and nightly cadence. SNR>>10 is ideal..."

Covington adds: "These systems show periodic variability on the spin period of the WD, usually on order of ~10 minutes. So, shorter exposure times are needed so the spin variability isn’t washed out. Previous AAVSO observations of these sources have had exposure times <60s, which is ideal. Also, accurate time tagging of the observations is required, so we can measure periodicities!"

Covington also notes that observers who have made a significant contribution to the research through their data will be considered for co-authorship.

Name RA (2000) Dec (2000) High state (typical) Range Observability Priority
V515 And 00 55 19.86 +46 12 57.0 14.75 V 14.3-16.0 V Early May - Mid Feb high
DW Cnc 07 58 53.11 +16 16 45.4 15.5 V 11.36 - 17.5 V Late Sep - Early May high
DO Dra 11 43 38.49 +71 41 20.6 15.0-15.5 V 10.0 - 17.2 V northern circumpolar high
V1223 Sgr 18 55 02.31 -31 09 49.6 13 V 11.2 CV - <16.8 B Mid Feb - Early Nov high
1RXS J213344.1+510725 (Cyg) 21 33 43.63 +51 07 24.7 15.25 V 14.6 - 16.4: V Mid Feb - Early Jan high
V1025 Cen 12 38 16.32 -38 42 45.8 15.25 V 15.1 - 17.5 G Mid Dec - Mid Aug medium
AO Psc 22 55 17.98 -03 10 39.98 13.3 V 13.0 - 15.0 V Late May - Early Feb medium

Charts with comparison stars for the targets may be created using the AAVSO Variable Star Plotter (VSP).

Please submit observations using the names given in the table to the AAVSO International Database.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Ava Covington.

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SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at:
 - Photometry/visual observations: https://www.aavso.org/webobs
 - Spectroscopy: https://www.aavso.org/apps/avspec/

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