João Calhau
@astrocalhau.bsky.social
The second rock from grandpa. Astronomy from Alentejo🇵🇹 to the World. Lancaster Uni alumnus. Post-doctoral researcher at INAF, Italy. Likes galaxy evolution, AGN,SFR, and Universe in general. Personal account; Opinions my own. astrocalhau.wordpress.com
Pretty sure you've seen them here before.
October 12, 2025 at 4:55 PM
Pretty sure you've seen them here before.
Pushed the Processing a bit more.
October 11, 2025 at 10:29 AM
Pushed the Processing a bit more.
To finish the night, I went for the Monkey Head Nebula, with ~2.7h integration. This one was harder to equalise especially because, as with every time I target nebulae, the freaking satellites decide to show up. Also something went wrong with the flats. Suspect some images had dew condensation.(5/7)
October 11, 2025 at 10:25 AM
To finish the night, I went for the Monkey Head Nebula, with ~2.7h integration. This one was harder to equalise especially because, as with every time I target nebulae, the freaking satellites decide to show up. Also something went wrong with the flats. Suspect some images had dew condensation.(5/7)
So in all I got two targets: First, we have around 2h of M33, the Triangulum galaxy. As with the next target, equalising the background was a nightmare because the Moon wanted in on the fun. (4/7)
October 11, 2025 at 10:25 AM
So in all I got two targets: First, we have around 2h of M33, the Triangulum galaxy. As with the next target, equalising the background was a nightmare because the Moon wanted in on the fun. (4/7)
Some of you may remember my Big Mount Woes. But you might not know I also had Smol Mount Woes. My SA GTi never worked properly. So I go a cat: (1/7)
October 11, 2025 at 10:25 AM
Some of you may remember my Big Mount Woes. But you might not know I also had Smol Mount Woes. My SA GTi never worked properly. So I go a cat: (1/7)
My mount's R.A. motor is coming back from inspection at JTW. Everything seems fine now so I just need to reassemble the mount once I get it. In the mean time here is 3h a of badly focused, tilt affected Iris Nebula. It was the only thing I managed to capture before breaking the mount...
October 3, 2025 at 8:39 PM
My mount's R.A. motor is coming back from inspection at JTW. Everything seems fine now so I just need to reassemble the mount once I get it. In the mean time here is 3h a of badly focused, tilt affected Iris Nebula. It was the only thing I managed to capture before breaking the mount...
My evening today.
September 6, 2025 at 2:38 PM
My evening today.
I love this image.
September 4, 2025 at 1:50 PM
I love this image.
So it seems like I actually managed to damage my mount with the crash. Any object away from the North pole gets crazy spikes in R.A. Fortunately JTW tells me the mounts are designed to be easy to repair and that I should not get a big bill to pay. (1/4)
August 30, 2025 at 9:59 AM
So it seems like I actually managed to damage my mount with the crash. Any object away from the North pole gets crazy spikes in R.A. Fortunately JTW tells me the mounts are designed to be easy to repair and that I should not get a big bill to pay. (1/4)
We continue our journey of trying to figure out the mount. A lot of wind and a sudden onset of clouds cut the night short. But there was still time for 1h of M20. Tried star re-synthesis as I couldn't get round stars (either due to mount or wind). Don't like it, always looks fake but it might be me.
August 19, 2025 at 3:31 PM
We continue our journey of trying to figure out the mount. A lot of wind and a sudden onset of clouds cut the night short. But there was still time for 1h of M20. Tried star re-synthesis as I couldn't get round stars (either due to mount or wind). Don't like it, always looks fake but it might be me.
...while the breaks were disengaged, which led to the R.A. axis crashing hard against the side of the mount. I am coordinating with JTW Astronomy, the manufacturer, to figure out if something is damaged. Sometimes R.A. has really bad trailing. You can see it here in this gamma cas nebula (2/5)
August 14, 2025 at 7:26 PM
...while the breaks were disengaged, which led to the R.A. axis crashing hard against the side of the mount. I am coordinating with JTW Astronomy, the manufacturer, to figure out if something is damaged. Sometimes R.A. has really bad trailing. You can see it here in this gamma cas nebula (2/5)
Two hours of the Iris Nebula, taken last night. Overlaid you can still see at least two instances of the scourge of the night sky: satellite trails. Still haven't managed to figure out the tilt of the coma corrector and to make matters worse a distraction led to me leaving the mount unattended (1/5)
August 14, 2025 at 7:26 PM
Two hours of the Iris Nebula, taken last night. Overlaid you can still see at least two instances of the scourge of the night sky: satellite trails. Still haven't managed to figure out the tilt of the coma corrector and to make matters worse a distraction led to me leaving the mount unattended (1/5)
Let's see how it continues going forward. For now, here are some pictures. The Deer Lick Group is 60 min last night. I forwent the previous integrations since the elongated stars would force me to artificially correct their PSF and I hate doing that. Bode's galaxy is around 2h. 3/3
August 5, 2025 at 12:21 PM
Let's see how it continues going forward. For now, here are some pictures. The Deer Lick Group is 60 min last night. I forwent the previous integrations since the elongated stars would force me to artificially correct their PSF and I hate doing that. Bode's galaxy is around 2h. 3/3
On the other hand, Bode's galaxy, closer to the pole, had rounder stars and I actually took 40 minutes of it _without_ guiding. SO I have no idea yet whether the mount is performing well or not. 3/4
August 2, 2025 at 12:20 PM
On the other hand, Bode's galaxy, closer to the pole, had rounder stars and I actually took 40 minutes of it _without_ guiding. SO I have no idea yet whether the mount is performing well or not. 3/4
2h of Deer Lick group had to have star resynthesis done, which I hate on general principle but it was the only way to correct for the elongated stars. 2/4
August 2, 2025 at 12:20 PM
2h of Deer Lick group had to have star resynthesis done, which I hate on general principle but it was the only way to correct for the elongated stars. 2/4
I am cautiously optimistic that the turning the focuser upside down trick may have worked. Still to early to tell though: sky-s too bright still. Half an our more of waiting at least.
July 30, 2025 at 8:36 PM
I am cautiously optimistic that the turning the focuser upside down trick may have worked. Still to early to tell though: sky-s too bright still. Half an our more of waiting at least.
Doesn't look that impressive, right? Slightly unfocused, with tilt ruining the coma correction, and a photobomb from the ever present satellites. But what if I told you this is a 2 min integration, unguided, at 1200mm focal length?
July 15, 2025 at 12:14 AM
Doesn't look that impressive, right? Slightly unfocused, with tilt ruining the coma correction, and a photobomb from the ever present satellites. But what if I told you this is a 2 min integration, unguided, at 1200mm focal length?
Sometimes, @eggstronomer.bsky.social , you include a space frog in your drawings and end up making actual merchandise.
Pros:
-Bigger than I thought (was expecting B4, got A4);
-Has Captain.
Cons:
-Has soft cover (though I did not check for a hard cover option, so that's on me)
Verdict: Positive
Pros:
-Bigger than I thought (was expecting B4, got A4);
-Has Captain.
Cons:
-Has soft cover (though I did not check for a hard cover option, so that's on me)
Verdict: Positive
July 14, 2025 at 11:36 AM
Sometimes, @eggstronomer.bsky.social , you include a space frog in your drawings and end up making actual merchandise.
Pros:
-Bigger than I thought (was expecting B4, got A4);
-Has Captain.
Cons:
-Has soft cover (though I did not check for a hard cover option, so that's on me)
Verdict: Positive
Pros:
-Bigger than I thought (was expecting B4, got A4);
-Has Captain.
Cons:
-Has soft cover (though I did not check for a hard cover option, so that's on me)
Verdict: Positive
I was tempted to quote Ozymandias but, considering what happened to the statue, I'd rather not.
July 7, 2025 at 2:36 PM
I was tempted to quote Ozymandias but, considering what happened to the statue, I'd rather not.
If you take a look at this plot you'll see what I am talking about: the dashed 3sigma line is the limit of detection in the X-rays. Anything below that does not get seen by Chandra. Now you can try to use stacking to go deeper which is what the squares are.
June 20, 2025 at 12:31 PM
If you take a look at this plot you'll see what I am talking about: the dashed 3sigma line is the limit of detection in the X-rays. Anything below that does not get seen by Chandra. Now you can try to use stacking to go deeper which is what the squares are.
I take a break from my diet for one day to eat the breakfast of champions of the Saint's season here in Portugal: Brenhol/Farturas, the Portuguese, _superior_ version of what the spanish call "churro" (we call it that too, but churro is much smaller/thinner and thus inferior).
June 15, 2025 at 7:54 AM
I take a break from my diet for one day to eat the breakfast of champions of the Saint's season here in Portugal: Brenhol/Farturas, the Portuguese, _superior_ version of what the spanish call "churro" (we call it that too, but churro is much smaller/thinner and thus inferior).
June 11, 2025 at 2:12 PM
Mine: upload.wikimedia.org/wikipedia/co...
Actually my families. It was the same age as me. We retired it some 10 years ago because it was impossible to get replacement parts. Still my favourite car to drive to this day.
Actually my families. It was the same age as me. We retired it some 10 years ago because it was impossible to get replacement parts. Still my favourite car to drive to this day.
May 19, 2025 at 6:13 PM
Mine: upload.wikimedia.org/wikipedia/co...
Actually my families. It was the same age as me. We retired it some 10 years ago because it was impossible to get replacement parts. Still my favourite car to drive to this day.
Actually my families. It was the same age as me. We retired it some 10 years ago because it was impossible to get replacement parts. Still my favourite car to drive to this day.