Lesedi Project Wiki

This wiki is for construction of a spectrograph on the 1-m Lesedi telescope in Sutherland. We anticipate future wikis for the user manual and for technical support.
The SAAO and LJMU (Liverpool John Moores University) are collaborating on the project.
The instrument is based on SPRAT (Spectrograph for Rapid Acquisition of Transients), which is currently operating robotically on the 2-m Liverpool Telescope on La Palma.

Project Team

Instrument PI: Iain Steele (LJMU; I.A.Steele@ljmu.ac.uk)

Instrument Scientists: Helen Jermak (h.e.jermak@ljmu.ac.uk)/ Andrjez Piascik (LJMU; A.S.Piascik@ljmu.ac.uk)

Mechanical Engineer: Stuart Bates (LJMU; S.D.Bates@ljmu.ac.uk)

Software Engineer: Chris Mottram (LJMU; C.Mottram@ljmu.ac.uk)

Data Pipeline: Marco Lam (LJMU; C.Y.Lam@ljmu.ac.uk)

Local Co-PIs: Amanda Sickafoose (amanda@saao.ac.za) & Hannah Worters (hannah@saao.ac.za)

Local Electronics Engineer: Hitesh Gajjar (hitesh@saao.ac.za)

Local Mechanical Engineesr:James O'Connor (joc@saao.ac.za) and Egan Loubser (egan@saao.ac.za)

Local Software Engineer: Carel van Gend (carel@saao.ac.za)

The link to the 2017 October 27 Skype kick-off presentation: https://www.dropbox.com/s/lcr54nkvtusdh69/SAAO-SPRAT-KICKOFF.pptx?dl=0 (includes references to the SPIE paper and Zej's thesis)

Point was raised that (rather than comount SHOC and this new spectrograph) we could use an iXon camera in the SPRAT system, add filter wheels, and effectively use it as SHOC when the slit, grating, and prisms are out of beam. The iXon has 1024 x 13-micron pixels as opposed to the iDus 1024 x 26-micron pixels. A test was performed at LT in the week of 15 Dec., in which the 85 mm f/1.8 camera lens was swapped out with a 50 mm Nikon f/1.4. The result from an arc was 7.70 Å/channel, central wavelength 6009.04 Å, range 4073.64 – 8018.33 Å. This range could be tweaked by tilting the camera slightly.

Some more details 50mmLensTest

Point raised by Stu at 12 Feb. 2019 Skype about filter wheel insertion into collimated beam causing flexture. James thinks that if the design can stay within the original structure envelope, and we are smart about orientation, the current stiffness might suffice. Alternatives to consider are (1) mounting a filter wheel near the entrance to the instrument or (2) separate SPRAT/SHOC mountings, by removing SPRAT and disconnecting the camera to reattach on the port.