Tracking the Artemis II Lunar mission using TU Delft's MISO telescope

Artemis II imaged with the TU Delft 41.5-cm MISO telescope on 8 April 2026 

'track & stack' of 13 images on the Spacecraft movement. Artemis II is the dot in the yellow circle.

 

I was only two years old when, in December of 1972, Apollo 17 left the Moon, so I don't remember it. But untill last week it was the last time in my lifetime that humans had entered and left the Lunarsphere. So for me, as a nominal "consciously just post-Apollo person", the crewed Lunar flyby of Artemis II 'Integrity' this week was exciting and new. Humans flying to the Moon again!

Of course, as a satellite tracker, it would be nice to capture something of that yourself: not from a TV screen, but as an actual observation. And since shortly, I have access to a nice tool for that: our new MISO telescope ("Multiple Input Single Output'), part of the SCOMlab on the rooftop of our Delft University of Technology Faculty of Aerospace Engineering. It is a 41.5-cm F8 Aluna Ritchey-Chretien telescope on a planewave L500 mount, realised by my colleague Rudolf Saathof for experiments with laser satellite communication. Rudolf involved me in the acquisition process and as a result, the telescope got a configuration to make it also useful for SSA/SOT when not being used for lasersatcom. I specifically want to use this telescope for XGEO/CisLunar observations in the future.

 

TU Delft 41.5-cm MISO telescope

MISO telescope dome on the roof of the TU Delft Aerospace Engineering Faculty

TU Delft MISO 41.5-cm telescope

 

Unfortunately the ARTEMIS II flight trajectory during this mission was not very favourable for the Netherlands, with the Moon (its target) very low in the sky in this season. Over the full mission it barely came over the horizon, and initially weather was not quite cooperative as well.

On the night of April 7/8 2026, a day after the Lunar flyby, with Artemis II homebound but still close to one Lunar distance from Earth, weather prospects were good. Although I had my doubts (unjustified, as it turned out!), Rudolf encouraged me to try to capture ARTEMIS in the early morning of April 8.

Conditions were not very encouraging: the spacecraft would reach a maximum elevation of no more than 8.8 degrees (!) over the horizon, it would be twilight already by that time, and the waning gibbous moon would be a mere 15 degrees distant. Prospects of success looked dim to me. Yet, I decided to go for it, and downloaded the ephemeride predictions for that night through JPL HORIZONS.

I only recently have had my training on the MISO telescope from our technician Martin. Much of the system is still in the commissioning phase (and I still  have to create good flats and darks for example, as this calibration imagery is not yet existent), and it still has its occasional quirks and glitches. This would be only the second time I would use the system on my own, via a remote connection from my home to the dome and instrument: and this deep into the night I'd rather not get Martin out of his bed if things went south. So I was a bit nervous. 

I logged in at about 4 am local time, and started the process of going through the checklist, powering up and activating the dome, telescope and sensors, opening the dustcover and dome doors, followed by some time spent on focussing and finding the best camera settings. Then I moved the telescope to where Artemis II should be, only 8.7 degrees over the horizon (...!). After initially trying 1x1 binning, I moved to 4x4 binning and started to snap 10-second unfiltered images with the QHY600 MM PRO camera that is attached to the prime focus of the telescope.

After transferring the FITS files from the observatory server to my laptop at home, I looked through them. From a previous observing run, I already had created a configuration file for the telescope/camera combination for Astrometrica, my favourite astrometric software. I created a 'blink' (animated sequence, to look for moving objects) of four of the images in Astrometrica, obtained near 3:34 UTC (5:34 am local time), around the start of nautical twilight. 

And next my heart skipped a beat: there was a faint but unmistakable moving dot right where ARTEMIS should be! Hallelujah!  This was very cool!

 

Artemis II imaged with the TU Delft 41.5-cm MISO telescope on 8 April 2026 

The image above shows the 'blink' I created of four 10-second exposures that were taken over a 1.5 minute timespan, with Artemis II visible as a faint moving dot. 

I frankly did not expect the attempt to be successful, so I definitely was very positively surprised by this! The spacecraft turned out to be around magnitude +14, brighter than I had expected and that helped. The sky at low elevation was clear, and our telescope is located on a high-rise at 55 meters above the surrounding landscape, which also helps (a bit). Yet, the influence of atmospheric turbulence and extinction at such a low sky elevation is well visible in the imagery.

The image below is composed of 13 images (each a 10-second exposure) taken some 20 minutes earlier, where I have used the 'track and stack' method, stacking the images with each image shifted in the direction of movement of the spacecraft. As a result, the stars become trails, but the spacecraft is still a dot, and because it combines the light collected over 13 x 10 seconds, Artemis II is much better visible now. It is the dot in the yellow circle:

 

'track & stack' of 13 images on the Spacecraft movement. Artemis II is the dot in the yellow circle.

(this image was created without flat- and dark substraction, which shows, as it has vignetting and some obnoxious "dust donuts". Not the prettiest picture, but happy with the result).

Artemis was at a whopping range of 359 000 km (pretty much still one Lunar distance) from the observatory at that time!

At the moment of writing, Artemis II is still on its way back to Earth. The capsule with crew should reenter the earth atmosphere near 00:00 UTC on the night of 10-11 April 2026 (April 10 local time on the US west coast), having separated from the Command module around 23:44 23:33 UTC (April 10). It then parachutes down for a splashdown in the ocean near San Diego. 

Below, I have created a map showing the ground-projected return trajectory. It is based on vector and event timeline data from NASA and a ballistic continuation of the last predicted vector with Tudat towards the splashdown area. The red boxes are the exclusion zones from Navigational Warning NAVAREA XII 232/26 and NAVAREA XII 242/26: they represent the areas where the Command Module reenters into the atmosphere, and the Crew Capsule splashdown area some 35 km out of the California coast.

(updated map, as a new exlusion area in front of the California coast was added in Navigational Warning NAVAREA XII 242/26, and the map is now based on NASA provided trajectory and event data rather than JPL HORIZONS).

UPDATED MAP. Click to enlarge

Note that this is a ground-projected trajectory, and in the early part of the approach (before 23:00 UTC) the spacecraft is still at a large distance. The seemingly accute "turn" around 22:00 UTC is not a real turn, but a perspective effect created by the earth surface rotating underneath the approach path, specifically parts of the earth surface that initially were "behind" the earth limb turning to the front as seen from the approaching spacecraft: and initially the effects of earth rotation nunder the trajectory being the major factor, the as Artemis comes closer, relative speed with respect to the Earth surface taking over.. 

 

click image to enlarge

Note: Astrometry from the observations is here, with a typo correction here.

OT - the Lunar Eclipse of 28 September 2015 from Leiden

click image to enlarge

Leiden had clear skies during the night of September 27-28, which meant a good view of the total Lunar Eclipse in the early morning of September 28.

For me, this eclipse occurred mostly at rooftop level, with the moon sinking from 34 degrees elevation at first contact with the umbra, to 11 degrees elevation at last contact with the umbra. During mid-totality, at 2:47 UT (4:47 am local time), the moon was at 21 degrees elevation, just disappearing behind the rooftops for me.

After setting up my Celestron C6, I could use the telescope until about 2:40 UT, when the moon disappeared behind the rooftops. I then went to my girlfriend's appartment, which (from the 2nd floor) has a good view Westwards, and continued photography with simpler means during the second half of the eclipse.

click image to enlarge: it is worth it!  See text for details

There I shot a series of images with the Canon EOS 60D and the EF 2.5/50 mm Macro lens on a tripod. 14 of these images, shot in 5-minute intervals, where then stacked to create the image above, which shows the second half of the eclipse from 03:15 UT to 04:20 UT, i.e. from late totality until just before last contact with the umbra. The lens was set at F5, camera on 250 ISO, and exposure times were 4 seconds at the start of the series, and 0.5 seconds at the end. It shows that you don't need a telescope to get nice pictures.

Of course, a telescope does allow for very fine pictures. Below are some results from the first half of the eclipse, taken with my Canon EOS 60D through my Celestron C6 (15 cm F/10 Schmidt-Cassegrain with F6.3 focal reducer):

Moon in penumbra, 01:04 UT, just before first contact with umbra
(1/200 second, 100 ISO) click image to enlarge

Entry in umbra progressing (1/50 second, 100 ISO), 01:30 UT
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Four minutes before totality (3.2 seconds, 200 ISO), 02:06 UT
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Totality, 02:32 UT (10 seconds, 800 ISO). Note two stars near top lunar disc
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This was a rather dark eclipse, to my estimate at the edge of L1/L2 on the Danjon Scale. The best moment for me was just before totality, when the moon sat just above the roof as a dark red-purple globe with a bright crescent on the lower edge: it looked a bit like Mars with a polar cap this way.

And by the way: NO! I refuse to go along with that "Super Blood Moon" nonsense. Puh-Lease!!!!

The "Blood Moon" denomer is actually of very questionable origin. It is not (contrary to what some people seem to think) an old folkloristic name for a Lunar eclipse, but is a denomer coined only a few years ago by two American Christian religious doomsday fanatics, who prophecied that the tetrad (series of four lunar eclipses each six months apart) starting with the eclipse of April 15, 2014 and ending with this eclipse of September 28, 2015, were a sign of the End of Times being near. They got their inspiration for this name from a sentence in the Bible, in the Book of Revelations.

Unfortunately, it seems everything in our modern society has to be expressed in ridiculous hyperbole nowadays. Ad to that media ignorant of the origin of the denomer "Blood Moon" with some religious crackpots, and you end up with horrible abominations like "Super Blood Moon" for what in essence was a nice and impressive, but in itself not particularly distinctive or rare Lunar eclipse...

Tracking distant space debris: more Chang'e 2 r/b observations

In my previous post I related how on May 7 a distant piece of Space junk was briefly mistaken for a Near Earth Asteroid. It concerned 2010-050B, the upper stage of the Long March 3C rocket that launched the Chinese Lunar mission Chang'e 2 in October 2010. This upper stage is moving in a trans-Lunar orbit, with apogee up to almost two Lunar distances away from Earth. The rocket stage is 12.4 by 3 meters large.

Yesterday May 10, I obtained new images of the object, using the 0.61-m Cassegrain telescope of Sierra Stars Observatory in California, USA. Above is an animated GIF of the images. My resulting astrometric data are here.

The object was near mag. +15.3, at a distance of almost 518 800 km at that time. For a comparison: the distance to earth of the moon varies between about 356 400 and 406 700 km. It is quite cool to image space junk at this large a distance!

Click image to enlarge

Using my May 10 observations combined with the May 7 observations by the Catalina Sky Survey (MPC 703) and Peter Starr in Warrumbungle (MPC Q65), I compute the following orbit for the object:

Orbital elements: 2010-050B Chang'e 2 r/b

Perigee 2015 May 22.689019 +/- 0.00747 TT 
= 16:32:11 (JD 2457165.189019) 
Epoch 2015 May 7.0 TT = JDT 2457149.5       Find_Orb 

M 198.75910 +/- 0.037        
n 10.27730942 +/- 0.00562

a 452220.817 +/- 165 km    Peri. 151.22410 +/- 0.028 
e 0.2197903 +/- 0.000308   Node 226.29285 +/- 0.00006
i 41.13389 +/- 0.00028 
  
q 352827.032 +/- 267 km    Q 551614.602 +/-  68 km       
P 35.03 d        H 28.1 

From 23 observations 2015 May 7-10; mean residual 0".307.

In TLE form:

Chang'e 2 r/b                                 352827 x 551615 km 
1 00000U         15127.00000000  .00000000  00000-0 00000-0 0 09
2 00000 41.1326 226.5090 2163618 150.9650 199.0248 0.02835833 01

For those people with access to a  sufficiently large instrument that want to try it themselves: efemerids for the object can be obtained here.

I plan to include this object in my periodic observations of distant satellites.

An ISS transit over the moon, and supernova SN 2014J again

Yesterday evening 9 February near 23:38:30 local time (22:38:30 UT) the International Space Station (ISS) made a transit in front of the moon, as seen from Leiden.

click image to enlarge

While the pass itself was good (the transit occured at 45 degrees elevation),  atmospheric conditions were far from perfect. The evening started clear, but as I was setting up the Celestron C6 fields of clouds came in. There was a strong wind rocking the telescope tube.While focussing on the moon, I noted that the seeing was abysmal: the lunar disc trembled and shivered from atmospheric turbulence, and rolling waves went over it, as if it was reflected on the surface of water. Test shots showed a much more blurred moon image, even at 1/400s, than I am used to with this instrument.

The final minutes were tense. A field of clouds came in and covered the moon minutes before the transit would start. Near the horizon I could see even thicker clouds. In the last two minutes before the transit, a gap in the scattered clouds appeared. At the moment supreme, 22:38:29 UT, the moon was right in this clear gap!

Three images out of a rapid burst series started a few seconds before the calculated transit time captured the ISS, as a ghostly dark bat in front of the moon. Nothwithstanding the bad seeing, wind and perhaps a slightly too long exposure time (1/400 second), structure is visible: the ISS solar panels are well visible for example.

The ISS was at a distance of 575 km over the British channel during the transit,  with an apparent size near 48". The transit took less than 1 second. As the ISS was not illuminated by the sun, it was visible as a dark silhouet (see the image above).


M82 and supernova SN 2014J

A few days earlier, in the evening of February 4, the sky was clear and I photographed galaxy M82 with supernova SN 2014J again. The wide field image below, a stack of 34 x 15 seconds at ISO 2000 also shows nearby spiral galaxy M81. The arrow points to the supernova:

click image to enlarge

OT - a new telescope and imaging the moon

Since 18 November I have done little in terms of satellite observing, for reasons outlined below. Therefore, a post that is slightly OT - but still astronomical in topic.

Generally bad weather over the past two months - lots of clouds, and even snow mid January - is one primary reason for my inactivity on the satellite observing front. Another is that mid-winter isn't the best period of the year at 52 N due to the "winter blackout" of many objects in LEO. Third, I am occupied these months by a few other things, including the "Super Secret Project" which I obviously can't talk about yet (but is very exciting).

The generally bad weather over December and January meant that I could not yet fully use my new toy. Near the start of December, I obtained myself a new telescope, partly with the proceeds of the Van der Bilt Prize. The telescope is a Celestron C6 Schmidt-Cassegrain (15 cm f=1500) on an SGT Advanced Goto equatorial mount. Here is me showing it off:

For quite a while I wanted a slightly bigger and optically better telescope than the simple Meade ETX-70 and small and very old 4.5" Newton I already had, yet found it just too expensive. The extra money from the Van der Bilt Prize meant it became just feasible for me to finally buy something better.

Since I have no option for a permanent setup and live small, it could not be a very large and heavy setup, so I choose this 6" Schmidt-Cassegrain (the mount is heavier than I expected though). Even though I have not been able to use it extensively yet, I so far like it very much!

Twice in January I could test it out on the moon. Here are some images shot on January 22nd. First, an old-fashioned single shot photograph of the moon disc (C6 prime focus with F6.3 flattener/reducer, and Canon EOS 60D, 1/160s at ISO 200). Seeing was quite mediocre, the air was not quite steady (the image was "wavy" as if reflected on the surface of water):

click image to enlarge

I also used the HD movie capabilities of my Canon EOS 60D to shoot a few short movies, and then stack frames from these movies using Registax. This results in a dramatic increase in detail. The images below are each the result of stacking 200 movie frames, selected out of movie sequences of ~550 frames each, and are my first ever experiments with Registax (which is quite complex to use for a novice):

click images to enlarge

Southern highlands: Clavius and Tycho

Northern part of Mare Imbrium with Sinus Iridium,

Plato and Vallis Alpes

Mare Humorum, Mare Nubium, with Gassendi

and Bullialdus

One of the intended primary goals for this telescope will be to observe asteroid occultations, with the WATEC 902H video camera plus GPS time inserter attached to it.Satellites are not the primary goal of this new instrument.

Defeated by the weather?

Just as the, perhaps last, visibility window of the by now world-famous USA 193 (06-057A) is starting here, weather has turned bad. Yesterday evening I could still observe the Keyhole USA 129 (96-072A) and the spent rocket boosters Lacrosse 5r (05-016B) and NOSS 3-4r (07-027B) under already hazy conditions: but now, heavy fog is hiding the skies and all what moves along it.

The USA 193 craziness is still continuing. Following the news that it will be shot with a missile somewhere next week - perhaps Wednesday/Thursday night, see also my ongoing updates here - this weblog is attracting an enormous amount of traffic again. Even more than the previous time USA 193 was in the news, late January.



Yesterday I was called by a journalist from the NRC, one of the "quality" newspapers of my country. This resulted in a short piece on USA 193, with some mention of our amateur observing work and me, in today's scientific pages.

This evening the NOS (our Dutch "BBC") called for a short informative chat, as they might do an item on it the coming days.

With all this, I should almost forget to report that I have been observing a lot the past days, taking advantage of three consecutive days of nice clear skies. Targets on these nights were the satellites and rocket bodies mentioned above, especially USA 129.

I also experimented further with photographing the moon through my ETX-70, in preparation for the lunar eclipse of coming Wednesday-Thursday night (that I am affraid I am going to lose to fog and/or clouds). With the help of a few euro of hardware I bought at a hardware store on Saturday, I made an extension to my telescope to firmly attach the camera to the eyepiece.

Below is one of the results. It is a mosaic composite of three images taken in the evening of February 17th. It is 2600 x 2600 pixels wide, 880 kB (click it to see it in full detail).

(click image to enlarge)

Here's a part-image of the southern highgland with a.o. the craters Tycho, Clavius and Schiller:

(click image to enlarge)

ISS and the Moon

Another clear evening yesterday. The moon is now becoming more and more prominent in the sky. The International Space Station (ISS) made a pass that brought it close to it in twilight at 18:44 local time (17:44 UTC). I made the photograph below with my Canon Ixus on maximum zoom and 2s exposure:

(click image to enlarge)

I also made another moon shot through my ETX-70 telescope:

(click image to enlarge)

Later that evening, telescopic points were obtained on the ELINT sat USA 32 and Keyhole sat USA 129.

Thin clouds spoiled the sats, but nice Moon this morning

When I came back from diner with friends around midnight, it was nicely clear. So I set the alarm-clock to see if I could catch the NOSS 3-4 duo in morning twilight.

Alas, when the alarm clock went off it turned out to be thinly veiled and impossible to observe satellites. So instead I took photographs of the waning moon. The best one is shown below. Like a few days ago, this one was made by just holding the Canon Ixus compact camera with its front lens on the eyepiece of the Meade ETX-70.

(click image to enlarge)