It's usually folly to plan a summer of imaging. Sure, clouds and smoke could spoil things, but why not give it a try? 2025 might just turn out to be an exceptional year! State Park camping and two star parties! Let's go!
APRIL/MAY
The first new moon of the 2025 camping season is on April 27th, a week after Easter. So any time within a few days of that should be dark enough for deep imaging. Likewise the dark moon in May, which may be better (i.e., warmer) for camping.
The late spring sky doesn't offer much to image at the focal length of my FSQ-106 (530 mm), aside from groups of galaxies and a few clusters. There is one wide-field subject that has always intrigued me: integrated flux nebulae, or IFN. Here's a nice summary of what IFN is and is not, and where to find it.
Probably the best known and most frequently imaged IFN is in the direction of M81 and M82. Instead of that I'll go for the IFN near Polaris.
Imaging near the north celestial pole has some interesting aspects. Because the apparent movement of stars there is so slow it's common for people to suggest not using autoguiding when imaging at relatively short focal lengths. To do without guiding you need a near-perfect polar alignment; a well-trained periodic error correction is very helpful, too. PoleMaster provides alignment that's close to perfect, so that's covered. But I do need to train PEC and that will be one of the first things I do this spring.
Associated with guiding is dithering, which I like to do. Is it possible to dither and not guide? Yes, with NINA's built-in dithering. I'll have to learn how to use this, and hope it works well. If it doesn't I'll probably just not dither.
I've never targeted anything so close to a celestial pole; A little testing suggests that my G-11 is fine with having NINA slew from counterweight-down it to the pole. What I'm not entirely comfortable with is NINA trying to center it there; will it get lost making excursions back and forth across the meridian? Is Polaris far enough from the pole to make centering a nonissue?
Regardless of where the target is there's always the question of what imaging gear to use. The key characteristics of IFN are that it's very low surface brightness and extensive in size. That sounds like a job for short focal length and fast focal ratio, right? Here are my best options for the optics:
- Takahashi FSQ-106 (FL 530 mm, f/5); Pinpoint stars, but smallish field and rather slow
- Takahashi FSQ-106 + focal reducer, (FL 387 mm, f/3.65); Pinpoint stars, very fast, but smallish field
- Tamron lens, (FL 135 mm, f/4.0); Fits NGC 188 in field, overmounted (not a bad thing), very fast, no autofocusing
This is one of my few images with the 135 mm lens. It's with a different CCD, but you get the idea. Aside from the upper right corner star shape is quite good. How well it works with my current camera is something to verify, along with what it might have for internal reflections when a bright star like Polaris is in the FOV. Clearly the 135 mm lens would be the option that's most forgiving of tracking errors. I really like that it would provide a wide enough field to include NGC 188.
And it's fast at f/4.
If the 135 doesn't work out I might go with the FSQ + focal reducer. Its ability to support autofocusing is some compensation for its small FOV. Maintaining the FSQ's focus will be important for dealing with the long, twilight to twilight sessions (6+ hours in April, about 4.5 hours in May). With a small lens like a 135, it's easy to minimize thermal FL change and prevent dew formation (as suggested by KathyAstro) by wrapping a long dew prevention strap around it.
Finally, there's the issue of exposure time. I'll probably use my standard 120 s @ gain 100 for luminance and try to collect as many frames as possible. If tracking is an issue, I can drop it to 60 s, but if stars stay nice and round, I might increase this up to as long as 300 s. Shorter exposures will be fine for the color channels; in fact, those might only be 60 s @ gain 0 to keep stars from saturating. Some experimentation is needed!
JUNE/JULY
The Nebraska Star Party typically occurs close to the end of July, a bit too late in the year for imaging my desired target of the Antares/Rho Ophiuchi region. In June the situation is much better, and a good time for imaging it comes after the third quarter moon of June 18. The Antares and Rho Ophiuchi nebulae should look fine together at 135 mm.
July is wide open for imaging much of the Milky Way, including the M8/M20 tandem. This pair will fit nicely into a single frame using the FSQ-106 with its focal reducer. Also available is M16, which nicely fits the FSQ native field.
LATE AUGUST
It's Northern Nights Star Fest time, and I'll continue collecting frames for the Soap Bubble. Recall that the Bubble had just started to show up with about six hours of frames collected in 2024. Continuing on this target in 2025 should put me over 12 hours of total exposure. Barring losing time to more Aurorae. 😁
SEPTEMBER/OCTOBER
The Iowa Star Party (2025 date TBD) will be a good time to gather more frames for either the IFN, the Soap Bubble, or some other target that suggests itself. Another possible target is IC 348.
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Obligatory Power & Battery Update
As an Amazon Vine reviewer, I have been able to get the components needed to replace my old 100 W solar panel and charge controller with a smaller, much lighter 50 W unit. Thank you, Vine!
Today wasn't ideal (high haze and tree branches) but it managed to supply 35 W. The charge controller seemed to work fine, and in an hour it boosted a 10 Ah LiFePo4 battery at rest voltage 12.96 V to 13.26 V. The meter suggested 20 Wh had been added to the half-charged battery. That's compatible with the rest voltages.
The real test will be when the sky is fully clear and the panel gets hot in the sunlight. I'll take it camping and see what it can do.
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