Webb Telescope

Estimated field of view: 4 x 3 arc-minutes Image date: 2021-02-09

At last. A one night reprieve from wall to wall cloud. Starlight!

Cosmic Focus Observatory was all set up and ready to go. The thick clouds parted and were gone by 9 pm, exactly as the forecasts said they would. My main target was to spot the James Webb Space Telescope, if I could.

Not at all confident about identifying Webb, I began taking a thirty frame live stacked exposure of 44 minutes.

I knew Webb would be faint and I was expecting it to be relatively stationary over the exposure period. I was even half-expecting to take a second image a few days later to see if I could pick any movement. Just like I did with Pluto.

When the first frame arrived I scoured the image and all I could see were points of light. That was to be expected – but a the Voice of Negativity in my head was telling me that the job of later identifying Webb might be difficult.

After another couple of images had been added to the stack, I began scrutinising the image on high zoom – and I soon noticed that one of the faintest star-like points was smudging.

It was in the right spot, so could this be Webb? Is its motion that obvious, so quickly? The Voice in my head sneered: “Do you really expect this spacecraft, only 1.5m kilometres away, not to be moving relative to the sky? The Earth is moving along its orbit (and spinning), while Webb is orbiting Lagrange 2. Did you not research all this properly before you started?”

Feeling embarrassed, I did a quick search and was surprised to find the size of Webb’s journey around Lagrange Point 2. It’s distance from L2 varies between 250,000 and 832,000 km, and one orbit takes about 6 months. So of course it’s moving relative to the stars, even without factoring the Earth’s own motion!

Back to the image on the monitor, which was building up nicely. The smudge was lengthening and it became obvious that this was indeed the amazing Webb Telescope moving across the starry background.

This is the full size image (it’s clickable). Webb is just below centre near the fourth star at the top of the “S” asterism but the chances are you won’t spot it.

Webb Telescope, 2022-02-09. 44 minutes exposure. Click to enlarge.
Field of view: 38.4 x 25.5 arcmin
© Roger Powell

Needle in a haystack? Well, after digital enlargement it does begin to show up:

Zoomed view showing motion of Webb Telescope in 44 minutes.
2022-02-09 Click to enlarge.
Field of view: 8 x 7 arcmin (est).
© Roger Powell

How faint is Webb?

It’s not very bright, is it? I don’t have much experience in estimating magnitudes and all I have to go on is the big red tinged star upper right in this final image. It is Tycho-2 768-1163-1 at magnitude +11.92. A hundred times fainter is five magnitudes so I would estimate Webb to be about five magnitudes dimmer, so roughly +16 magnitude.


You can find the current location of the Webb Telescope from your own coordinates > HERE <


For the record, the clouds came back with a vengeance the next day.

All images © Roger Powell

Telescope:Meade LX-90 200mm Schmidt-Cassegrain
(deforked); 2000 mm f/l @ f/10.
Optics:Astronomik light pollution filter.
Mount & Guiding:SkyWatcher EQ6-R Pro mount.
Imaging camera:ZWO ASI 071 MC cooled.

The Blind Astronomer

Cosmic Focus Observatory

34° South

Above us only sky….

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10 Comments

  1. A very exciting investigation you undertook, Roger. Speaking from a light-polluted location with no hope of seeing a ~sixteenth magnitude object, I appreciate you sharing your thought process and the end result of finding Webb.

    Liked by 1 person

    1. Hi Paul. Thank you.
      I’m well and truly inside suburban Sydney. My 200mm schmidt-cassegrain is rated visually for magnitude 14 but seems to achieve at least 16 photographically, with the help of a light pollution filter.
      Webb is going to outdo Hubble for science but for beautiful images I’ll be interested to see how the false colours work in infra-red.

      Liked by 1 person

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