JWST Countdown To Terror 😳

[johninderby]

7 minutes ago, Mr Spock said:

It's good the pallets are done. This was always going to be one of the more difficult deployments.

Full sunshield deployment isn’t due until +5.5 days so not out of the woods yet. 

[Rob_Jn]

Anyone got a good ephemeris for JWST, I get an error on JPL Horizons 😐 tried quite a few settings but all the same error message

 

[kirkster501]

1 hour ago, Rob_Jn said:

Anyone got a good ephemeris for JWST, I get an error on JPL Horizons 😐 tried quite a few settings but all the same error message

 

Set the Ephemeris time to 10 days.  30 days does not work.

[kirkster501]

This is the current location and will drift to the east a few minutes of arc per day over the next ten days.  Would dearly loved to have imaged it but there is no chance with the weather - as per usual with anything remote exciting happening in the world of astronomy in the UK.

You just run the Ephemeris tool to get the JWST coordinates for your location and then enter them into Stellarium.   Remember parallax has a slight effect but less so now that it has been going for a bit and is 350k miles out.

Edited December 29, 2021 by kirkster501

[kirkster501]

2 hours ago, johninderby said:

Full sunshield deployment isn’t due until +5.5 days so not out of the woods yet. 

Yep.  Tower assembly has to raise up and the momentum flap deployed before the telescopic wings extend in a couple of days time.

[Rob_Jn]

37 minutes ago, kirkster501 said:

Set the Ephemeris time to 10 days.  30 days does not work.

Brilliant, thanks that worked 😊👍

[jjohnson3803]

A little levity, although I do empathize with her feelings:

Dr. Becky watches the launch

 

 

[Sunshine]

On 27/12/2021 at 04:55, kirkster501 said:

They said that even in tests, very occasionally the sunshield didn’t fully work.

Oh no! don’t say that! It isn’t helping my anxiety about the whole thing!

[Sunshine]

26 minutes ago, kirkster501 said:

This is the current location and will drift to the east a few minutes of arc per day over the next ten days.  Would dearly loved to have imaged it but there is no chance with the weather - as per usual with anything remote exciting happening in the world of astronomy in the UK.

You just run the Ephemeris tool to get the JWST coordinates for your location and then enter them into Stellarium.   Remember parallax has a slight effect but less so now that it has been going for a bit and is 350k miles out.

Not sure what its apparent magnitude is but it would be awesome to see it through a 4" refractor.

[jjohnson3803]

4 minutes ago, Sunshine said:

Not sure what its apparent magnitude is but it would be awesome to see it through a 4" refractor.

I believe the BAA photo info listed it currently at around m=14.4.

[Sunshine]

2 minutes ago, jjohnson3803 said:

I believe the BAA photo info listed it currently at around m=14.4.

Oh, well that puts it out of range for me, bummer.

[kirkster501]

2 minutes ago, jjohnson3803 said:

I believe the BAA photo info listed it currently at around m=14.4.

That is my understanding too.  Should be easy to image it with a few five minute subs to show the movement.  For visual I'd imagine you'd need a quite detailed atlas.

JWST is not available on The SkyLive as yet Space Probes | TheSkyLive.com

[tomato]

Will the apparent brightness increase when the sun shield is fully deployed? I suppose it depends on it’s orientation with respect to us looking at it from Earth?

I might just get a chance to capture a few subs tonight…

Edited December 29, 2021 by tomato

[kirkster501]

There looks to be a tiny bit of blue here and there in the sky.  I think it'd only need five or six 300s subs.

[Laurieast]

Temperature data is now available!

 

TEMPERATURES

Temperature control is a vital aspect of Webb's design, engineering and operations. Of the many temperature monitoring points on the observatory, this page displays 2 "hot side" and 2 "cold side" temperatures that are a good indication of overall temperature status and trends.

+

The temperatures displayed on the hot side of the observatory are located on the sunshield structure and spacecraft bus. . The temperatures displayed on the cold side of the observatory are located on the primary mirror and instrument (ISIM) module radiator. You can read more about the observatory and its subsystems on this page. They are labelled with the following letters on the display (note: these labels will pop up if you hover your mouse over the display):

 

• a) Sunshield UPS Average Temperature (hot side: Sunshield Structure)
• b) Spacecraft Equipment Panel Average Temperature (hot side: Spacecraft Bus)
• c) Primary Mirror Average Temperature (cold side: Mirrors)
• d) Instrument Radiator Temperature (cold side: ISIM)

 

There are many more temperature sensors on the observatory that our engineers monitor throughout the deployment, commissioning and operations processes. The data points shown here give a good overall indication of the temperature trends on each side of the sunshield as we move through deployment and commissioning. They illustrate the great contrast between the hot and cold sides of the spacecraft and the incredible engineering and effectiveness of the sunshield. These temperature observations are reported daily from actual spacecraft telemetry data. Temperature values will continue to be reported in the months that follow the completed deployment as the spacecraft cools to operational values.

[Laurieast]

NASA Says Webb’s Excess Fuel Likely to Extend its Lifetime Expectations

https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-extend-its-lifetime-expectations/

Webb Team Begins Process of Extending Deployable Tower Assembly

https://blogs.nasa.gov/webb/2021/12/29/webb-team-begins-process-of-extending-deployable-tower-assembly/

[kirkster501]

Thanks for sharing Laurence.

[kirkster501]

Lovely ambient music by Joseph Beg.

[Zermelo]

41 minutes ago, Laurieast said:

NASA Says Webb’s Excess Fuel Likely to Extend its Lifetime Expectations

https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-extend-its-lifetime-expectations/

Ariane rocks it!

[kirkster501]

20 minutes ago, Zermelo said:

Ariane rocks it!

Yes indeed, the accuracy of the Ariane launcher could have added years to the mission.  I watched a video about this on YouTube a few weeks ago and they said it was crucial beyond crucial that the trajectory Ariane put it on was correct.   It has to be placed in an exact place at an exact distance at an exact trime and a few feet per minute too fast could blow the entire mission.

Let's not get too excited just yet though and hope a lot of the "twirls" and "shimmies" are not needed to get a potentially jammed sunshield opened up, thereby wasting precious fuel.

[Stuart1971]

Just a bit of fun, the JWST takes its first image….😂😂

 

[kirkster501]

One of these stars is JWST.  I just can't get a proper 100% focus though since it's forever clouding over.  Will keep trying.

Edited December 29, 2021 by kirkster501

[Sunshine]

Question about Webb's orbit and orientation, because the mirrors will always be facing away from the sun with a huge sunshield behind it, how will they image any portions of sky/targets that lie behind it? it cant swing around cause the sun will fry the mirrors. Maybe those targets will be imaged when it has made a 180 degree orbit around the sun? where it will be directly opposite to where it was in its solar orbit therefore exposing an area that was previously behind, I dunno.

Am i making any sense? its hard to describe.

Edited December 29, 2021 by Sunshine

[kirkster501]

12 minutes ago, Sunshine said:

Question about Webb's orbit and orientation, because the mirrors will always be facing away from the sun with a huge sunshield behind it, how will they image any portions of sky/targets that lie behind it? it cant swing around cause the sun will fry the mirrors. Maybe those targets will be imaged when it has made a 180 degree orbit around the sun? where it will be directly opposite to where it was in its solar orbit therefore exposing an area that was previously behind, I dunno.

Am i making any sense? its hard to describe.

That is correct.  It can only image things that are in a cone 120-150 degrees wide centred on the sky opposite The Sun; at no point must any of the JWST telescope optics or "shadow side" components be exposed to the direct sun.  This means that if it could image now it would be 60 degrees either side of Orion (i.e. opposite the Sun in the sky).  When it - hopefully - opens for operations next year it will be able to observe SagA* at the centre of the galaxy.  First objects are a reproduce of the Ultra Deep Field in Fornax - 160 hours of scope time! - and M82, another 80 hours.

[kirkster501]

^^^indeed, scope operations are very carefully planned such that the scope is not slewing here , there and everywhere between random targets of the researchers. Target selection is extremely carefully managed so that only the tiniest whiff - literally a thimbleful -  of fuel is needed to move the scope between closely adjacent objects in the sky to preserve the precious fuel.