2022 April 18

Observer’s Challenge – Observe the James Webb Space Telescope

David Swan

As of mid-April, commissioning of the James Webb Space Telescope continues without significant hiccough. It is now ‘at’ the place where it will carry out it its observations: orbiting L2, an Earth-Sun Lagrange point.

Nick James started a forum thread last year to encourage BAA members to follow the telescope from its launch through to L2. Many interesting observations were reported, including astrometry of the upper stage of the launch vehicle and high-cadence time-series photometry of the telescope. Nick spoke about some of the members’ work at the BAA meeting on 22 Jan.

The apparent movement in our sky of the JWST will be large: over the course of the year, it will cover approximately 70 degrees in declination. There is a good window in the next few weeks ­– when the moon gets out of the way – to record further observations of the JWST before it is lost to us in the UK over the summer. It will then become well-placed again in the autumn.

At around magnitude 17, the JWST will be out of the range of visual observers (unless one has access to a very large aperture scope!), but within range of many amateur imagers. For the dates below (the end of April) the sky motion is ~ 3” / min, so subs of up to one minute to get good SNR should be OK. (If you are wanting to determine precise astrometry, the subs will have to be shorter.)

Date	RA	Dec
2022/04/22	15 24 20.4	-04 46 44
2022/04/24	15 37 58.0	-06 38 07
2022/04/26	15 50 55.8	-08 25 53
2022/04/28	16 03 14.0	-10 09 55
2022/04/30	16 14 54.5	-11 50 16

From NASA JPL Horizons. Calculated for an observer in Leeds, UK; time 00:00 UT; epoch J2000.

Suggested types of observation:

• Show the movement of the JWST against the stellar background
• Record high-cadence time-series photometry
• Perform low-resolution spectroscopy

Clear skies!

David Swan; Tynemouth, UK

Teaser Image: Artist impression of the James Webb Space Telescope. Credit: NASA.