Mu Serpentis - or is it though?

 

Image acquired with the Star Adventurer mounted 66mm Altair Refractor, the new 500 lines/mm spectrometer and the QHY5-11mono camera. Credit :Jolene McSquint-Fleming.

Calibrated Line Profiles and Reference Profile for an A07 class star together with a stretched coloured Synthetic Spectrum Strip. Credit: Jolene McSquint-Fleming.

New 500 lines/mm spectrometer designed and constructed in the Observatory clean room by Jolene McSquint- Fleming the JPO's Instrumentation Engineer.

"The weather continues to be very unfavorable for astronomy, with high level cloud preventing us imaging the gas giant planets Jupiter and Saturn. 

Over the summer, Jolene has addressed some of the optical aberrations associated with using a 500 line diffraction grating as a simple filter cell.  We did not want to permanently adapt the QHY5-11 camera for spectroscopy and so designed a 3d printed block to allow it to be brought very close to the imaging chip at the optimum angle for a first order spectrum at 550nm. This appears to have minimised 'fish tailing' of the spectral image and aided obtaining focus upon the spectrum rather than the star. 

On the 7th of July 2021 we tried the new spectrometer out using the 66mm Altair Astro refractor.  As the sky was quite light, only a few stars on the meridian were visible to the naked eye, so we chose one at random for the trial.

One of the not immediately appreciable downsides of using a 500 line diffraction grating is that, as the spectrum is more spread out than when using  a 100 or 200 line grating, it produces a significantly dimmer image. Possibly this will be improved by using the 127mm refractor, by stacking more light frames and by taking darks and flats. 

We prepped the spectral image using the freeware IRIS and then had a go at producing an initial calibrated profile using the excellent BASS software. The Observatory is indebted to the generous, skilled and intelligent individuals that devise and collaborate in the development of scientific software which is made accessible for free use. Thank you Christian. B and John. P!

Having obtained a profile we guessed, from the presence of strong Hydrogen Balmer lines, that the star in question is an A type star. We then used Stellarium to look for bright  A type stars that were observable to the naked eye and to the south near the meridian on 07-07-2021. The best candidate  is the A07 star Mu Serpentis.

Next up we intend to:

Image Vega and obtain a camera response curve for the set up.

Become more proficient in the use of BASS software.

Complete a half constructed 3d printed 100 lines/mm spectrometer for obtaining spectra from fainter stars.

Come up with a rudimentary grating design to address extended objects of interest.

Experiment with a fibre-optic link between the telescope and a spectrometer." - Kurt  Thrust current Director of the Jodrell Plank Observatory