Update on comet C/2026 A1 (MAPS)

On its way to a close encounter with the Sun, with perihelion expected on April 4–5, 2026, comet MAPS is steadily brightening. By mid-March, it had reached magnitude 10—still far too faint to spot without optical aid. However, as it moves deeper into the inner solar system, and if it survives its close approach, it could make an appearance in Earth’s skies around Easter.

Gerald Rhemann and Michael Jäger - March 10, 2026.

In early April, some models predict it might shine as brightly as Venus, the brightest planet. But that’s likely an optimistic guess. It will probably reach a magnitude of 1 to -2, making it about as bright as some of the more prominent stars. These estimates are based on its brightness (18th magnitude) when it was still twice Earth’s distance from the sun. Magnitude 18 is far too faint to see with the naked eye, but it’s actually quite bright for a comet at that distance.

Sungrazers can be breathtaking, but their close proximity to the sun makes them hard to see. Even if MAPS glows as brightly as Venus, it will remain near the sun and low on the horizon. Here's a diagram showing the location of MAPS on April 4, at 6:30pm. Notice how close it is to the sun and only about 13° in altitude. Even at magnitude -4 (Venus' brightness) the sun is 1 billion times brighter! Still, there’s a chance we could witness something truly historic.

If it survives it's close approach to the sun, those in the northern hemisphere will have a better chance to see it as it starts to climb out of the sun's glare. On April 8th it will be 10° high at sunset.

April 8, 7:30pm

As the month progresses, MAPS will get a bit higher in somewhat darker skies. At 8:00pm on April 15th, altough still low in the western sky (10-15° high), it should become easier to see as the sun is now 4° below the horizon.

By the end of April, it begins to drop in altitude and will grow much dimmer as it moves away from the vicinity of the sun.

Plan ahead and pick a spot with a clear view of the western horizon. We just might get to see another Ikeya–Seki.

Soldiers Delight Star Party - March 21, 2026 - Topic: The James Webb Space Telescope

 

Soldiers Delight Star Party - March 21, 2026

Don't miss the next SD Star Party:

"Unlocking the Cosmic Secrets: The James Webb Space Telescope"

Join us on a captivating journey beyond the visible spectrum! The James Webb Space Telescope (JWST), one of humanity’s latest cosmic sentinels, has already started to revolutionize our understanding of the universe. Imagine peering through the veil of dust and time, witnessing the birth of galaxies, the dance of exoplanets, and the cosmic symphony of star formation. In this exclusive talk, we’ll delve into the cutting-edge science, awe-inspiring innovations, and mind-boggling discoveries that JWST has provided. Buckle up, stargazers—Webb has already challenged our understanding of the Universe and is continuing to unveil the cosmos as never before!

All ages welcome.

All programs rain or shine. Time machines will be provided by the Westminster Astronomy Club.

You can find out about special local events by contacting us at https://www.westminsterastro.org/

Date: Saturday, March 21, 2026

Time: 6:30 p.m. - 8:30 p.m. Eastern Daylight Time (EDT)

Location: Soldiers Delight Environmental Area - Visitor Center

5100 Deer Park Rd.

Owings Mills, MD 21117

Stretching and HDR Processing

Although my previous post using M42, the Orion Nebula, was to demonstrate image stacking in astrophotography, the image based on the 80x8sec stack is quite good and so I decided to redo some of the post processing and make a few additional improvements.

First, the nebula suffers from the large dynamic range in brightness between the inner core and the subtle outer regions, i.e., the core tends to get 'blown out'. This is true of a number of objects that have bright interior regions, such as galaxy cores, and in this case, bright nebulae. M42 has the famous Trapezium Cluster, a young open star cluster with four equally bright stars in a tight orientation, located in the center of the nebula. But because the nebula itself is so bright the cluster is hard to make out.

Second, I did not properly account for the background when applying the Multiscale Adaptive Stretch (MAS) and so some of the fainter outer regions of the gases did not appear as I would like. 

But before showing the result of these improvements I need to explain the concept of stretching.

Stretching  

Both stacking and stretching are always necessary in astrophotography post processing. Whereas stacking helps increase the SNR of the image and gain the benefit of a long integration time without having to take extremely long exposures, stretching is necessary to make the image visible.

In astrophotography, stretching an image means remapping the brightness values in the photo so that very faint details become visible, without blowing out the bright parts. It’s a core processing step for deep‑sky images.

When you capture the night sky (especially galaxies, nebulae, or dust clouds), the camera records light in a linear way. If you have twice the light hitting the sensor, the pixel value where the light is recorded is twice as high. However, most of the signal from faint objects is packed very close to black. Only stars and bright cores of nebulae and galaxies stand out in the image. In fact, if you looked at the raw or stacked image, it usually appears almost totally black, maybe with a few bright stars. But there is a lot of data there; it just isn't spread across the range the human eye can perceive.

Stretching applies a non‑linear transformation that expands the dark tones, where most of the image data resides and compresses the bright tones. In other words, it separates faint structures from the background.

MAS is a form of stretching that has recently been introduced in PixInsight, my processing software of choice. Similar to the other tools in PixInsight I have used in the past, it stretches the image so that the faint data can be brought to light. However, MAS also provides some additional options to make the stretch even better and offers the user a lot of flexibility when it comes to contrast preservation, enhancement of faint details and removal of the background sky glow.

HDR Multiscale Transformation

Handling the large dynamic range in brightness of an object is accomplished with an application of a High Dynamic Range transformation process. Usually this is done by stacking subs with small exposures (to capture the bright areas) and large exposures (for the dimmer regions). The stacking process will then provide a more pleasing result preserving detail across extreme brightness differences. The HDR Multiscale transformation process allows one to do this without the need of exposing subs with different exposure times. You can apply it to the single final stacked image.

Applying the Processes

Here is the original image of M42 right out of the camera with minimal initial post processing. As expected, it is almost totally black. The bright inner core is visible as is the Trapezium cluster.

Applying the MAS stretch reveals the data lurking down in the image. This is the same image as the 80x8sec image in my previous post. The nebula now stands out (note the Trapezium is swamped by the bright emission gases in the core). 

However, the default settings on MAS use the complete image to determine the mean background intensity and so it was not handling the removal of the background as best as it could. By selecting an area of the image devoid of any real signal (I used a section in the lower left) and providing that as the background reference for MAS, the result is much better - the outer extent of the nebula can now be seen.

However, the core of the nebula is now even brighter, and the details of the gas structures is almost non-existent. This is the problem with M42 - the range of brightness between the lightest regions and darkest regions is very large. And this is where HDR comes in. Applying HDRMT with just the right settings (a trial and error manual process by the way) we get the following image.

A run through with Paint Shop Pro yields the final result, ready for printing and hanging on my office wall!. All the wonderful elements of this famous nebula are now clearly visible, from the inner core detail to the outer edges and even the Trapezium.

 

The Science of Image Stacking - Experimenting with Sub Exposure Times

Stacking multiple astrophotography images—often called image stacking or integration—is one of the most important techniques in modern astronomy imaging. It allows photographers to reveal faint celestial details that would be lost in a single exposure.

Instead of taking one very long exposure (which can be ruined by a plane crossing the field or wind moving the equipment), astrophotographers take many shorter exposures of the same object (a galaxy, nebula, star field, or planet). Each image records the signal (real light from stars and deep-sky objects) as well as noise (random fluctuations from the sensor, heat, electronics, and sky background).

Because astronomical objects are effectively static over short time spans, these multiple images contain the same signal but different random noise patterns. Since the signal is consistent across images it adds together as the individual subs are built up, but the noise is random and averages out toward zero. As a result, the signal-to-noise ratio (SNR) improves by the square root of the number of images stacked (√N).

Indeed, the sky background, due to excessive light pollution, limits exposures of under 3-5 minutes in order to prevent the object from being swamped out. In very dark skies this is not generally a problem; but near cities where streetlights and buildings are dense, it is.

Noise is the biggest enemy in low-light imaging. Stacking reduces random noise far more effectively than any single long exposure, producing smoother backgrounds and cleaner detail. In addition, stacking allows bright stars and faint structures to coexist in the same image without clipping highlights or crushing shadows, revealing more tonal information across the scene.

In summary, image stacking works because math beats physics: Physics limits how much light a single exposure can collect without noise while statistics allow many imperfect images to combine into one high-quality result allowing modern amateur astrophotographers to produce images that rival professional observatory photographs from decades ago.

Of course, you need to determine an appropriate exposure time to capture the needed photons (if no photons are picked up by the sensor it doesn't matter how many subs you stack in the end). But you can limit the exposure time by quite a bit depending on the object of interest.

As an example of just how well this works, I imaged the famous Orion Nebula, M42, with my EdgeHD telescope in Hyperstar mode (an f/2 optic train). This nebula is the brightest nebula in the night sky. A single 60 second exposure can give you a nice result (albeit a bit noisy). A ten-minute exposure would really bring out the detail. But 10 minutes is way too long of an exposure in the light polluted sky of my backyard. The science of stacking, however, claims that a stack of ten, 1-minute exposures would provide the same image as a single ten-minute exposure with the added benefit of reduced noise, hence better SNR.

Here are three final photos of the Orion Nebula taken with differing sub-exposures and stacked to provide the total integration time of ten minutes.

 

10x60sec

40x15sec

80x8sec

Can you see any differences? In fact, looking at the original images (these are reduced size JPGs for posting here) the 80x8sec stacked version is noticeably better in terms of SNR, although the post processing software I use has some terrific noise reduction tools that were used in the creation of these images.

The drawbacks of this are few, but worth mentioning. It takes 8 times the storage to hold the 80 8-sec subs vs the 10 60-sec subs and the post processing time (and required storage on the computer) also goes up. But this is a small price to pay for such wonderful results.

Next time I'll target a fairly faint nebula to demonstrate how this really shines!