Following JWST through Orion to L2

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  • #575123
    Nick James
    Participant

    The James Webb Space Telescope is now scheduled for launch on Ariane 5 flight VA256 on Christmas eve at at 12:20 UTC.

    Following launch it should be a relatively easy object for us to follow as it transfers to L2. The magnitude is a bit uncertain but Gaia was 10th magnitude on the first night after launch, fading to 18th mag 3 nights later and around 20-21 at L2. Gaia was particularly faint, WMAP and Planck were both between 18-19 at L2. JWST is much bigger than these so should be brighter but this will depend on the exact solar aspect angle and properties of the sunshield. It will be interesting to see how bright (or not) it is.

    You can get an ephemeris from JPL Horizons. Just search for JWST and make sure to configure your observatory location since there will be considerable parallax early on. Attached is the ephemeris for my observatory (it is a text file, just change the ending to txt to view it). The first night after launch it has a very high apparent motion in Orion but should be an easy visual target. It stays in Orion until Jan 4 when it moves into Monoceros.

    Please post reports and images on your members’ page. Let’s see how far we can follow it. 

    #585026
    Paul Leyland
    Participant

    I will see what I can do, but as Tacande Observatory won’t be back in operation until February at the very earliest it will likely take relatively long duration imaging. Gaia is still within range of my kit (must try for it one day) so JWST shouldn’t be too much of a problem.

    Thanks for suggesting this target!

    #585029
    Grant Privett
    Participant

    Nicely placed for observation from the UK then. I’m looking forward to imaging this.

    How far apart will it be from the vehicle that launched it?

    #585030
    Nick James
    Participant

    It is very well placed for us and everyone but that is not entirely a coincidence. It is going in the anti-solar direction and the launch is scheduled to avoid getting too close to the Moon. Winter is definitely good for us in the northern hemisphere since L2 is currently high in the sky.

    There’s not much detail available about what will happen to the cryogenic upper stage following JWST separation which occurs at around 30 minutes after launch. JWST is directly injected into a transfer orbit to L2 so the upper stage will probably be close by but it will probably do some form of deflection burn and JWST itself will do its first course correction at L+12.5h so the two will drift apart. There is another course correction burn scheduled for L+60h. I don’t know how bright the upper stage will be but on the first few nights I would expect it would be detectable and fairly close to the spacecraft. I’ve imaged Centaur upper stages at ranges of more than 700,000 km and the Falcon 9 upper stage at 400,000km but the Ariane upper stage is smaller I think. The Centaurs also do propellant dumps which can be interesting to watch. I assume that the Ariane stage does something similar.

    #585031
    Neil Morrison
    Participant

     Thank you for the  heads up Nick.  The 26th looks an interesting point to start this imaging project. 

    I  plan to get  some new reference images of  Orion’s Belt using  a 85 mm F1.4 Samyang lens  for semi wide angle shots and also  some other  frames  of a narrower angle perhaps  the 500mm F 5.5 Star Sky  weather permitting  and  hopefully with the launch on  schedule and  clear weather   possibly spot the   JWST on the  images  as an interloper . . 

    #585032
    owen brazell
    Participant

    Unfortunately due to weather conditions the launch is delayed until at least Saturday and from what I have seen the forecasts for Korou do not look much better then. Not sure how this impacts where it can be seen. Bit of a shame with the rocket and satellite now ready the weather throws its usual spanner in the works.

    #585033
    Daryl Dobbs
    Participant

    Hopefully the weather will improve but the link below is to the NASA press release 

    https://www.nasa.gov/feature/james-webb-space-telescope-launch-update

    #585034
    Alex Pratt
    Participant

    From a selfish point of view I welcome the delay in launching JWST, at least until there’s a chance of any clearing in this interminable cloud cover to observe it. The JWST will get to L2 before I see any stars again…!

    Alex.

    #585035
    Paul Leyland
    Participant

    Just Wait, Still Terrestrial.

    #585036
    Nick James
    Participant

    Since the launch window opens at about the same solar time every day the chart should remain valid by just offsetting the dates, so, for instance, if it does go up on Christmas day then substitute 27.0 for 26.0 and so on. There will be an eastward drift of 4 mins a day in RA as well. In any case the JPL Horizons ephemeris will be updated to reflect the actual launch time.

    #585037
    Tim Haymes
    Participant

    When i enter the info asked for i get a load of stuff about JWST in red, but no list.  Is there a glitch with the system?

    #585038
    Nick James
    Participant

    Most likely you have a start time set before the launch time. The last line of all those error messages is:

    No ephemeris for target “James Webb Space Telescope (spacecraft)” prior to A.D. 2021-DEC-25 12:48:00.0000 UT

    #585039
    Nick James
    Participant

    Here is a revised chart for the current Dec 25 launch. You can see that it follows pretty much the same path, shifted around 4 minutes east a day.  

    #585041
    David Swan
    Participant

    Happy Christmas all! Fingers crossed that JWST launches without a hitch today, and that the whole sequence of further manoeuvres (and unpacking) goes as planned. The weather forecast for NE England over the next week shows a lot of cloud unfortunately. But I would love to image it whilst en route to L2.

    #585042
    Alex Pratt
    Participant

    Now watching the pre-launch coverage on NASA TV…   🙂

    Alex.

    #585043
    Peter Mulligan
    Participant

    It has just unfurled its Solar array great launch

    #585044
    Paul Leyland
    Participant

    3 minutes early…

    #585045
    Nick James
    Participant

    It was great to see the solar array deployment live via the upper stage camera. The launch certainly added some excitement to Christmas lunch and the Ariane 5 performed very well. Now, if only we could get a clear patch between the torrential rain…

    #585046
    Nick James
    Participant

    Denis Buczynski (Tarbatness) managed to get the spacecraft tonight at mag 12.3 which is a bit fainter than I expected. Luca Buzzi reports via MPML that the upper stage is around the same magnitude and about half a degree west of the spacecraft. There will probably be a significant effect on the magnitude when the sunshade gets deployed. Total washout here.

    #585047
    Neil Morrison
    Participant

    The Launch certainty added a new dimension to cooking Xmas lunch, dashing between  Kitchen and  Nasa TV on Computer.

    Its  the best Xmas present the Astronomical Community could wish for  lets  hope that it continues to deliver its potential as it  slowly   deploys.  

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