Slitless Spectroscopy

September 27, 2021.

September 21, 2021.  Finally identified most of the excited coronal lines in the spectrum.  In my earlier spectra I have misidentified some of the lines.

Here's all three spectra I have so far, Aug 13, 16 and 24:

August 24, 2021.  Got another spectrum of the nova yesterday. Looks like the Helium line emissions have increased relative to the Hydrogen line emissions since my last spectrum taken on August 16. Are we witnessing 4 H ---> He thermonuclear fusion of the hydrogen falling onto the surface of the white dwarf? Hope to get another few spectra this week to see if the trend continues.

Here is the comparison with published spectra of helium:

Here is the calibrated spectrum:

The spot to the left is the zero order spectrum from the light that is not diffracted by the Star Analyser 100 line per mm grating.  The bright knots, left to right on the spectrum are Hb=486.1nm, He=587.5, and Ha=656.3nm. The spectrum was scanned and calibrated, using the non-linear calibration but using a first order fit because grating dispersion is linear with wavelength.  The zero order spectrum at 0 nm and both hydrogen lines were used in the calibration shown below:

August 16, 2021.  I replaced the ASI294MC with the ASI178MM grating assembly (see drawing above) and lined up the C14 on nova RS Ophiuchi.  I took a 628 second video of 1000 frames using an exposure of 0.63 seconds and a gain of 407.  The video was processed in Autostakkert3, aligning and stacking the best 50% of the frames.  The not very colorful result is shown below:

Here is the calibrated spectrum:

The blue spot to the left is Hb=486.1nm, The yellow spot is He=587.5, and the bright red spot on the right is Ha=656.3nm.  The spectrum was converted to a monochrome FITS file and was scanned by RSpec and calibrated using the non-linear second order calibration method using Ha at 656.3 nm, Hb at 486.1 nm and the Helium feature in the yellow at 587.5 nm.  Three calibration points were needed because spectra produced by prismatic dispersion are non-linear.  The calibration is shown below:

August 13, 2021.  I located recurrent nova RS Ophiuchi at RA=17h50m09s and Dec=-06°48'18" with the 7.25" Schupmann with the ASI183MC at the f/14 focus and detuned the field mirror from its normal setting by 4 full turns clockwise on the yaw micrometer.  This produced a spectrum with a faint continuum background and a very bright emission feature in the red end of the spectrum and a somewhat fainter one in the blue end.  Other even fainter features were present in the yellow and the blue/green regions.  A 300 second long .avi file was taken using a 0.3 second exposure and a gain of 450.  The video was processed in Autostakkert 3, keeping the best 90% of the frames to give this result: