Observation by Mike Harlow: T CrB Spectrum

Uploaded by

Mike Harlow

Observer

Mike Harlow

Observed

2024 May 09 - 22:00

Uploaded

2024 May 09 - 23:22

Objects

T-CrB
Spectrum

Equipment

12 inch F/3.6 Astrograph
Starlight Xpress H16 CCD (2048 x 2048 pxl)
26cm diameter, 6 degree objective prism
Silica plate in place of luminance filter

Exposure

20 x 20 seconds

Location

Ipswich, UK

Target name

T CrB

Title

T CrB Spectrum

About this image

First light with my new double prism setup. Two 3 degree prisms mounted together to double the dispersion for a given focal length. And what better target than T CrB to get a spectrum before outburst.

T CrB itself shows typical metal oxide bands compared to an ordinary A-Type spectrum at top right with Balmer lines and atmospheric bands in the near IR.

There are many other spectra of T CrB in the BAA Spectroscopy database. See for example recent spectra by Boyd and Sims. Note that the narrow H-alpha emission feature is only just resolved in my spectrum.

Field of view ~ 46 x 46 arc minutes with north, and red, to the right. The field can be identified by comparing with David Strange's colour image.

Note: Index matching oil was used between the two prisms to eliminate any reflections from the two inner surfaces. Rather than very expensive commercial matching oil I used olive oil from the kitchen...it's about 500 times cheaper...!!! (Index n=1.46 compared to commercial matching oil n=1.52 which would have been very slightly better).

Files associated with this observation

TCrB_spectrum_20240509.jpg (201.2 kB)

Like this image

James Weightman, Jeremy Shears, Andy Wilson, Robin Leadbeater

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