Alert Notice 777: EH Lib observations needed now to correlate with spectroscopy

June 6, 2022

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Dr. Eric Hintz (Brigham Young University (BYU), AAVSO SPP Section Leader), Jarrod Hansen (BYU), and Scott Call (BYU) request AAVSO observers' assistance in observing the delta Sct variable EH Lib in support of spectroscopic observations being obtained this week for a Master's Thesis research project.

Coverage is requested beginning immediately and continuing through June 15. Key nights for observations are June 08-09 and June 09-10.

Dr. Hintz writes: "Using 1.2-m and 3.5-m telescopes we are obtaining simultaneous IR and optical spectra that cover roughly from 4500 Angstroms to the end of IR K band.  These will be obtained over at least one pulsation cycle on each of June 8th and 9th of 2022. This will be at a cadence of about 10 to 15 minutes, depending on which telescope. These spectra will be flux calibrated and we will be looking at changes over the pulsations cycle in the spectral lines and the overall flux curve. To do this well, we need to have accurate phase information.  While EH Lib is a well established High Amplitude delta Scuti, it would be best if we had photometry during the same period to get the best phase information.  It is also valuable to compare the spectroscopic data to phased photometric data in any standard filter.

"This overall project is also about one-half of a Master's Thesis project. Being able to compare the spectroscopy to photometric measurements will greatly enhance the final thesis."

"Photometry observations of any cadence would be valuable and they don’t need to be at the same cadence throughout.  However, what would be the most valuable would be light curves that cover at least one pulsation cycle, or about 2.5 hours. This target has an amplitude of about 0.43 mag in that 2 hour time period, so errors in the 0.01 range would be okay, with a preference for errors more in the 0.005 range.

"CCD and PEP observations are preferred. Light curves in any standard optical Johnson or Sloan filter would be great. If someone can do a J band (or H band) curve that would be fantastic. While DSLR data are a bit harder to interpret, they could still provide other insights to the results, so we are fine with those types of observations as well. Visual observations are welcome to supplement the light curve."

Coordinates (J2000.0): R.A.14 58 55.92  Dec. -00 56 53.0    (from VSX page for EH Lib)
Range: 9.35 - 10.08 V;  10.09 B; 9.88 g'

Finder charts with comparison stars for EH LIB may be created using the AAVSO Variable Star Plotter (VSP).

Please submit your observations to the AAVSO International Database using the name EH LIB.

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using material provided by Eric Hintz.



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