Zooming in on the Christmas Tree Cluster

For the first time in what seems like years (actually months), we have a warm, clear nights on March 12 and 14, and I used two astrophotographic "rigs" at once.

One project was to get an ultra-portable setup ready to take into the country to hunt integrated flux nebulosity. That consists of a camera tripod, an iOptron SkyTracker that I've had for more than a decade, and a camera and lens that I've also had for more than a decade (Canon 60Da), and a couple of lenses that are also getting on in years. New image processing software (BlurXTerminator) squeezes a bit more quality out of almost any camera lens by cleaning up residual optical imperfections near the corners, as well as minor tracking inaccuracies, and PixInsight can now reject poorly tracked frames automatically.

The first lens I tried was my vintage-1970 Nikon 50-mm f/2. Here's a wide-field view of Monoceros, from the Rosette Nebula at the bottom up to a snake-like dark nebula at the top, a stack of 92 (yes, 92) 30-second exposures at ISO 800 and f/2.8. This is not the full frame but is almost the whole left half of the picture, and as you can see, with modern processing the image is sharp indeed. Since this was taken in town, it doesn't show any particularly hard-to-get objects.

Left of center is a star cluster (NGC 2422) that looks like an upside-down Christmas tree, and that brings me to last night's (March 14) photo session. I moved up to my Sigma 105/2.8 DG EX lens, vintage 2005, nowadays assisted by a black rubber band to keep its focuser from rotating under the force of gravity or vibration, since it has loosened up a bit with age. At f/2.8 it is as sharp as we could wish, and the tracking is good. Here's the field of the Christmas Tree cluster:

Jupiter, done properly

This evening (March 5) I used the 8-inch telescope to photograph Jupiter properly (without the f/7 reducer, and with a camera with smaller pixels). This is a stack of the best 25% of 9,105 video frames with a ToupTek 678 color camera.

I also had my first visual astronomy session, brief though it was, since both eyes fully recovered from cataract surgery and the blurry spots that troubled me for a few weeks. An ophthalmologist with whom I correspond about astronomy has suggested that they were stray particles left over from removing the old lens, and adhering to the posterior capsule or something near it, and they dissolved. We may never know, but they're gone.

I can truthfully describe the implanted lenses as better than new. There are no unwelcome optical effects when I look through the eyepiece, and even at 400×, which is almost too high a power for this telescope, I get a much smoother view than even 20 years ago; the artificial lens doesn't have the specks and spots that were always inherent in the natural one.

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Dual-booting Linux with Windows 11

On my do-everything 14-inch ThinkPad, which I take to the library and everywhere else I do work, I needed to actually run Linux, not just WSL. So I set it up to dual-boot. Lots of web pages tell you how to do this; where I will mention some unobvious details.

It's not quite the same as dual-booting Windows 10 with Linux. Most things are the same, but what has changed is that under Windows 11, BitLocker disk encryption is more or less compulsory. You can turn it off, but Windows updates are liable to turn it on again. And I want to have it in place, so that if someone steals my laptop or obtains the flash drive from it, they won't be able to read my data.

My first attempt was a disaster — Linux was happy as a clam (or penguin), GRUB worked so that I could choose operating systems when booting, but Windows asked for the BitLocker recovery key every time it booted. Fortunately I had my key available (I had to go home to get it), but that wasn't acceptable. What was wrong?!

I searched online for answers and ended up completely undoing the Linux installation — deleting the partition it was installed on, using bootsect to fix Windows (subtle; it involved mounting the boot sector as drive S), and even hiding "ubuntu" in the UEFI boot menu.

Well, toward the end of that process I found out what was wrong. Windows demands the BitLocker key if Secure Boot is turned off in BIOS (UEFI). The problem may not have been Linux at all! But installing Linux with the wrong options can apparently cause Secure Boot to turn off, and wiping out every last trace of Linux doesn't fix it.

So the second time, I did everything right:

• Used Disk Manager to shrink my main Windows partition, gaining a 128-MB free-space partition into which to install Linux.
• Suspended BitLocker temporarily, knowing it would turn back on the next time Windows started up.
• Restarted and pressed F1 to get into the UEFI menu; made sure Secure Boot was turned on.
• Booted Linux Mint from a bootable USB drive and chose "Install Linux Mint."
• For the installation options I chose "Something else" and directed it to my 128-MB partition. (It might well have found that if I had taken the default; I don't know; but that's how I've done it in the past.)
• Also in the installation options, I made sure Secure Boot was enabled. This required making up a password, which I stored away carefully though I don't know why I'll need it. Linux is nowadays compatible with Secure Boot.

That gave me a successful Linux installation, with GRUB for choosing operating systems.

There were three remaining concerns.

Time zones: If Windows sets the system clock automatically (as mine does), Linux has to be told to run on local time rather than UT (GMT), or it will reset the system clock several hours off. Nowadays all you need is the command:

sudo timedatectl set-local-rtc 1

File sharing: Linux can't see a BitLocker-protected disk, and I think I like it that way. (A stranger with Linux on a jump drive wouldn't be able to read my data either.) Fortunately, my ThinkPad T490s has a strange provision for keeping a micro SD card installed more or less permanently, though it's easy to get out, much like changing a SIM card in a phone. I have a 256-GB card there, and both Linux and Windows can see it and write on it. That's how I get files back and forth from one OS to the other.

I did not opt for Linux disk encryption, so I will limit the amount of confidential data that I store in Linux. If this becomes a concern, I can presumably turn disk encryption on.

Mouse: You can't pair a Bluetooth mouse with more than one operating system; don't try. Also, a recent-model Logitech mouse that supports both Bluetooth and USB wireless turns out to have a complicated pairing process that I never got working as desired. (Hint about Logitech mice: A full reset requires taking the battery out! It retains some memory about pairing when switched off.)

What worked was to get the old, simple, plain-USB-wireless mouse (Logitech M310) from one of my other computers. It emulates a wired mouse and has no pairing protocol.

The one spooky thing about the M310, which other Linux users have noted, is that sometimes the mouse wheel doesn't work under Linux unless you take the battery out for a moment and put it back in. Strange error in some Linux driver, I suppose, perhaps to be fixed in the future.

So that's how I spent a lot of time for two afternoons!

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Some astrophotography at last

Due to a remarkable spell of bad weather, I did no astrophotography at all in January, and only finally got around to doing some on the last day of February. My main goal was to test guiding software and a guidescope (I'm trying out an unofficial fork of PHD2).

I had the Celestron 8 EdgeHD set up with the f/7 compressor and Altair 26C (24-megapixel) camera, but the gibbous moon was in the sky, so the first thing I did was take a picture of the moon. To be precise, I recorded 99 video frames, then stacked the best 75% (presumably 74 of them) and turned up the color saturation to bring out differences in the minerals on different parts of the moon's surface. Here's the result.