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Alert Notice 599: CI Aql monitoring needed in support of HST observations

October 1, 2017 : Dr. Edward Sion (Villanova University) has requested AAVSO observers' assistance in monitoring the recurrent nova CI Aql in support of observations with the Hubble Space Telescope Cosmic Origins Spectrograph scheduled for October 30 - November 6, 2017. These observations are part of a study on short orbital period recurrent novae as Supernovae Type Ia progenitors.

It is essential to know 24 hours prior to the HST COS observations that CI Aql is not in outburst, in order to protect the instrumentation. Also, photometry is needed throughout the HST window to insure knowledge of the brightness of the system.

Observers are asked to monitor CI Aql with nightly snapshot images (V preferred) from now through November 30, and to report their observations promptly. Visual observations are welcome.

When the exact time of the HST observations is known, observers will be informed via an AAVSO Alert Notice and the forum thread for the campaign, so that the crucial positive observations showing the status of CI Aql 24 hours prior to that time can be obtained and reported.

CI Aql (Nova Aql 1917) has had recurrent outbursts in 1941 and 2000, brightening to V~8.5. At minimum it is V~16-16.5 or fainter.

Coordinates (2000.0): R.A. 18 52 03.57  Dec.  -01 28 39.4

Charts with a comparison star sequence for CI Aql may be created using the AAVSO Variable Star Plotter (VSP). Observers need to be aware that the field of view is complicated by some comparison stars appearing as close doubles.

Please submit observations to the AAVSO International Database using the name CI AQL.

This observing campaign is being followed on the AAVSO Campaigns and Observing Reports online forum at https://www.aavso.org/ci-aql-campaign-2017

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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