spectro-aras.com

This week I have made some first tests on AZ Cas at H alpha with my new 1200l/mm grating (LHIRES III, ATK314L+ and C11)
Resolution ~5000 (35um slit) SNR (0.25A bin) ~70 in a 1 hour exposure (3x20min)

The results look quite good and are in good agreement with Joan Guarro's using a similar setup (see attached)

I am also taking spectra of delta Cas for instrument response correction and to estimate the telluric line intensity (I think there may be too many lines in AZ Cas to be sure of making an accurate telluric line removal without this)

I can increase exposure time but the question is, should I reduce my slit width, trying to get better resolution or stay at the same resolution and improve SNR?

Cheers
Robin

I have made a second run using 2x binning and 2 hours exposure. the resolution is the same ~5000 but the SNR has improved to ~150. The repeatability is good (see attached)

The telluric lines cannot be used to check the calibration because of the complex spectrum of this star so careful calibration using neon lines is critical (I took neons at start end and middle of the run and saw changes of ~1 pixel. A neon before and after every 20 min exposure is probably advisable)

Robin