Searching for Comets Lemmon & SWAN
A once-in-a-lifetime double comet feature.
The sky that once told our story is fading. The darkness that shaped every dream, every question, every sense of wonder, is almost gone. It took billions of years for the universe to give us this view, and in a few generations, we have buried it in light. Our children will grow up thinking the night is empty. They’ll never know what it feels like to be swallowed by the stars, to feel the weight of infinity pressing softly against their skin. The real tragedy is knowing it will only fade further from us. And somewhere above all this glow, the stars are still waiting for us to remember them.
What promised to be a spectacular celestial event for astronomy enthusiasts like me turned into a cloudy and frustrating two-night affair on October 21 and 22. Despite ideal conditions coinciding with the new moon and the Orionid meteor shower, the rare appearance of two distinct comets, C/2025 A6 (Lemmon) and C/2025 R2 (SWAN), was ultimately obscured by inclement weather over areas in and around Hyderabad. But despite the disappointment of not getting the comets, I think I did get to see Lemmon briefly in a few photos, I was greeted by a spectacular sunset which I recorded in a timelapse included below.
I have recorded meteor showers earlier this year which you can read about here but those were the α-Centaurids’s meteor shower, which peaks around February 8th or 9th. The minor February Hydrids and Antherea showers have their peak activity mid-month. The α-Centaurids are the most prominent of these three, with an hourly rate of possibly 1 to 5 meteors. I was able to capture 10 meteors over a 11 hour timelapse.
What is the Orionid Meteor Shower
The Orionid meteor shower is an annual celestial event that occurs in October. It's caused when Earth passes through a stream of cosmic debris left behind by the famous Halley's Comet, officially known as 1P/Halley. This debris, consisting of tiny particles of dust and ice, burns up upon entering Earth's atmosphere, creating the streaks of light known as meteors or "shooting stars".
Origin: The Orionids originate from Halley's Comet, which orbits the sun approximately every 76 years. The Earth intersects this debris trail twice a year, once in May (creating the Eta Aquariid meteor shower) and again in October, producing the Orionids.
Radiant Point: The shower gets its name because the meteors appear to radiate from a point near the constellation Orion. This effect is an optical illusion, and the meteors can appear anywhere in the sky. To get the best view, it's actually better to look away from the constellation so you can see the longer, more spectacular streaks.
Speed and Appearance: Orionid meteors are known for their speed, entering the atmosphere at about 66 kilometers per second (41 miles per second). This high velocity creates bright, fast meteors that sometimes leave glowing, persistent trains of incandescent gas that last for a few seconds after the meteor has disappeared. Some can even appear as fireballs. In my blog here you can see one - the most prominent one - which was a true fireball.
Visibility: The Orionid meteor shower is visible from both the Northern and Southern hemispheres. It's best viewed in the hours after midnight, when the radiant is high in the sky, and is most visible under dark, clear skies away from city lights.
The 2025 Orionid meteor shower
The Orionid meteor shower peaked on the night of October 21–22, 2025. The timing was particularly favorable for observers this year because the peak coincided with a new moon, which meant darker skies and better visibility for fainter meteors. However stargazers in and around Hyderabad were unable to enjoy the celestial display due to inclement weather caused by the low-pressure area over the Bay of Bengal, which later evolved into Cyclone Montha. I was well away from the light pollution of Hyderabad and was hoping to capture the comets but could only return with these timelapses of the clouds and a spectacular sunset.
A once-in-a-lifetime double comet feature
The anticipation had been building for weeks as both Comet Lemmon (C/2025 A6) and Comet SWAN (C/2025 R2) are both long-period comets, making their near-Earth passes a once-in-a-millennium or even rarer event.
Comet Lemmon (C/2025 A6): This comet was discovered in January 2025 by the Mount Lemmon Survey in Arizona.
Origin: Like most long-period comets, Lemmon likely originated from the Oort Cloud, a distant theoretical spherical shell of billions of icy bodies that surrounds our solar system, marking its outermost boundary. It is believed to be the source of long-period comets and extends from about 2,000 to 100,000 astronomical units (AU) from the Sun. The Dutch astronomer Jan Oort first proposed its existence in 1950 to explain where long-period comets originate.
Orbit: Lemmon has a highly eccentric, or stretched-out, orbit. Its orbital period was originally estimated at 1,350 years, but a pass near Jupiter in April 2025 shortened it to approximately 1,150 years. This means its last visit to the inner solar system was in the 7th century AD - while we were building some of our stepwells, and its next won't be until around the year 3175. Besides, this comet is best visible in the Northern Hemisphere — a rare case. The orbit of C/2025 A6 is tilted by 143.7°, so the comet moves retrograde — opposite the planets’ usual direction — and approaches perihelion on a northern, retrograde path, favoring northern observers.
Appearance: On this approach, Comet Lemmon developed a striking greenish coma, a halo of gas and dust surrounding its nucleus. The green color is a result of diatomic carbon (:C=C:) in the comet's coma.
Visibility: By November 10, its maximum altitude will drop to about 16–19°, depending on the location. In the sky, the comet will be in the constellation Boötes in late October and closer to Ophiuchus in early November. Let’s talk about numbers. In astronomy, magnitude values work as follows: the lower the number, the brighter the object. The current forecast puts the peak brightness around magnitude 4 in late October, which would make Comet Lemmon a naked-eye object from dark locations and an easy target in binoculars.
So, despite being the best comet of 2025, Comet Lemmon won’t become a “great” comet, like NEOWISE or (arguably) Tsuchinshan-ATLAS. However, this comet is still way brighter than about 90% of comets visiting our Solar System, so I don’t intend to miss out! But remember, comets don’t follow scripts, so be prepared for surprises.
Is Comet Lemmon Visible to the Naked Eye?
Good news — Comet Lemmon can now be seen without binoculars!
Starting around October 20, people from different parts of the world reported that the comet became bright enough to spot with the naked eye. Some observers estimate C/2025 A6 has reached a magnitude of about 3.6, though more reliable data from COBS suggest it’s closer to 4. Still, it’s not an easy target — you’ll need a very dark, clear sky, far away from city lights. It won’t be visible from urban areas without equipment, but binoculars will make it easier to find.
Comet SWAN (C/2025 R2): Discovered in September 2025 by Ukrainian amateur astronomer Vladimir Bezugly using images from the Solar and Heliospheric Observatory's (SOHO) SWAN instrument.
Origin: As a long-period comet, SWAN is also believed to have originated from the Oort Cloud.
Orbit: SWAN orbits the Sun on an even longer path than Lemmon, with an orbital period estimated at over 22,000 years. This makes its latest visit an exceptionally rare occasion. Its next return is not anticipated for tens of thousands of years.
Characteristics: Although fainter than Lemmon, SWAN also showcased a bluish-green coma and tail.
Weather conditions prove uncooperative
The window for prime viewing of the two comets and the Orionid meteor shower occurred over the evenings of October 21 and 22, promising a captivating spectacle. However, the Indian Meteorological Department (IMD) was tracking a developing low-pressure area over the Bay of Bengal, which evolved into Cyclone Montha. The weather in Telangana during this period was a direct consequence of this larger meteorological system.
Regional Impact: The low-pressure area, which later intensified, brought extensive and persistent cloud cover not only to Hyderabad but across much of Telangana. In the days surrounding the prime viewing window, districts across southern, central, and northern Telangana, including Nagarkurnool, Nalgonda, and Ranga Reddy, experienced widespread moderate to heavy downpours.
Hyderabad Weather: The city itself was not spared, with the forecast indicating moderate to heavy rainfall, especially during the crucial late afternoon and evening hours when viewing conditions would have been optimal. The skies were filled with a thick, moisture-laden atmosphere that blocked out all but the brightest stars, making any form of celestial observation impossible.
My timelapse clearly illustrates the multiple layers of clouds and the speeds they were traveling at. Albeit for a brief interval, when there was a break in the clouds on the 22nd, immediately after sunset there is a green speck clearly visible in the sky. Was this Comet Lemmon? I could not make out a tail - most likely because I was on a fairly short interval to get pinpoint stars. Let me know in the comments either on my YouTube channel or here what you think.
How to photograph a comet
Despite the missed opportunity for Comets Lemmon and SWAN, situations like this help to prepare for future events. The following will help anyone interested in photographing comets in the future.
Equipment: A decent camera (DSLR or mirrorless with manual mode), a sturdy tripod, and a lens are essential. For more advanced photographers, a star tracker can enable longer exposures without streaking. I have all my gear listed here.
Settings:
Focus: Always use manual focus and achieve pinpoint sharpness on a bright star in live view. If possible use a Bahtinov Mask. Some use cases
Aperture: Shoot with the widest aperture (lowest f-number) the lens allows, such as f/1.8 or f/2.8, to gather maximum light. Also note that some lenses aren’t always sharp at their widest aperture - in such cases stop down once or twice.
ISO: Start with a moderate ISO (e.g., 800–3200) and adjust based on light conditions.
Shutter speed: I always use the NPF Rule to determine my shutter speed. The NPF rule is a more accurate astrophotography formula for calculating the maximum shutter speed to avoid star trails compared to the older “500 rule”. It accounts for a camera's specific N-aperture, P-pixel pitch, and focal length using the formula: Exposure Time (seconds) =
((35 * Aperture) + (30 * Pixel Pitch)) / Focal Length. This method is more precise because it considers the pixel density of the camera sensor, which is crucial for modern high-resolution cameras
Technique:
Shoot RAW: Capture images in RAW for maximum detail and flexibility in post-processing.
Take multiple images: Capturing many short exposures is the best way to get a clean image.
Image stacking: Specialized software like DeepSkyStacker or Siril can combine multiple comet images to enhance details and reduce noise.
Post-processing: The stacked images can be further processed in software like Adobe Photoshop to adjust contrast, color, and remove artifacts.
Composition: For more compelling images, consider incorporating interesting foreground elements like trees or landscapes. Shoot from a location with a clear view of the horizon and minimal light pollution. That said, in today’s scenario, especially in a country like India, unless you go to Ladakh, it is rather difficult to avoid a degree of light pollution wherever you go more so in the southern part of India.
What comets to look forward to in the near future
While the sight of Lemmon and SWAN may have been lost to the clouds, the night sky is full of opportunities for patient observers. Here are some upcoming comets to watch for, along with details on the best conditions and times to view or photograph them:
Comet 3I/ATLAS: This interstellar visitor is currently passing through our solar system but is not a naked-eye object. There is a lot of hype around it so keep a close watch.
Viewing: It will reappear in early December 2025, but you'll need an 8-inch or larger telescope or a telephoto lens.
Best Time to Photograph: In November and December 2025, it will be visible in the morning sky. Look for it before sunrise in the constellation Virgo and later in Leo.
Comet 24P/Schaumasse: A short-period comet that will make its closest approach to Earth in early January 2026.
Viewing: It's not expected to be a naked-eye comet but might be visible with binoculars, a small telescope or large telephoto lens from especially dark skies, reaching an estimated magnitude of 8.
Best Time to Photograph: It will be a morning object, so catch it in the hours before dawn. The days around January 4–6, 2026, when it passes closest to Earth, will offer the best opportunity.
Comet C/2024 E1 (Wierzchos): Another Oort cloud comet on a hyperbolic orbit.
Viewing: This comet will be visible with larger binoculars or a modest telescope, reaching around magnitude 8.5. Viewing from the Northern Hemisphere may be challenging due to low altitude, but a low-power, wide-field telescope could provide a better view. For photography I will choose to wait and see how it develops before committing a lens.
Best Time to Photograph: Its closest approach to Earth will be on February 17, 2026. The best times to capture it will be around its closest approach and during the early evening hours in February.
Comet 46P/Wirtanen: A Jupiter-family comet with a short 5.4-year orbital period. Its next perihelion is predicted for October 2029.
Viewing: During its 2018 appearance, it was barely visible to the unaided eye but was a beautiful sight through binoculars and small telescopes. Its next pass should offer a similar opportunity.
Best Time to Photograph: Keep an eye out for updates as its approach draws nearer. Past experience suggests the period around closest approach offers the best photographic opportunities.
The disappointment lingers, but for many, the anticipation itself was part of the fun. It is a shared experience that connects people to the wider universe and to each other. Despite the letdown, the stargazing community in Hyderabad is already looking forward to the next celestial event, hoping for clearer skies and a more generous view of the cosmic ballet.
The timelapse above was captured on 21st and 22nd October 2025 from around 6pm to about 10.30pm under Bortle Class 4 skies using a Canon 1Dx Mark ii and a combination of lenses. The time window was very small and I was basically standing and waiting for the clouds to clear from about 6pm. And when I finally saw it I wasn’t sure I was actually looking at the comet which brings me to the topic of light pollution and the impact it is having.
The devastating impact of light pollution
A recent study showed that about a third of the world’s population has never seen the Milky Way with their naked eye. But just a little bit over a hundred years ago everybody could see the Milky Way with their naked from the comfort of their garden or roof top. Today almost 70-80% of our population across the globe now lives in an area where they cannot see the Milky Way and there is a funny story about this around the earthquake in Los Angeles in 1994 which caused a power outage. The emergency services that morning were inundated with calls about a weird cloud in the sky. People thought aliens were coming!
That weird cloud turned out to be the Milky Way. They’d never seen it before and didn’t know what was going on and people were terrified.
Light Pollution Map - South India
Light Pollution Map - Hyderabad
The Bortle scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. John E. Bortle created the scale and published it in the February 2001 edition of Sky & Telescope magazine to help amateur astronomers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites. The scale ranges from Class 1, the darkest skies available on Earth, through Class 9, inner-city skies. It gives several criteria for each level beyond naked-eye limiting magnitude (NELM). The accuracy and utility of the scale have been questioned in recent research.
The images on the right are light pollution maps of Hyderabad and my location which is a Bortle Class 8/9 - Inner City Sky - and a light pollution map of South India just to put things in perspective. As you can see there are very few true dark sky sites left in the south of the country. I use the Dark Sky app when I need to find dark skies followed by a whole sequence of apps to find the stars or galaxies. But most times I am restricted to doing star trails from wherever I am and some of these I have shared in my Photo Gallery.
The image below is an illustration of the different skies of the Bortle Scale with the star field visibility clear. Incidentally I have been beneath a Bortle Class 1 sky and the experience cannot be described in words. I could see the Milky Way and millions of stars, the ISS and the Star Link satellite train with my naked eyes. These were unforgettable times when, a few years back, I was lying on my back on a deserted beach near a temple town looking at a star field stretching from my head to my feet and once, not so long ago in Japan, on the Otowa Bridge, which traverses the Setsuri River as it flows through Tsurui Village, in sub zero temperatures hoping the temperature would drop to -15 degree Celsius or more so the difference in the air and water temperatures would create fog and my photos would have the “mood“. Read more about the stunning Red Crowned Cranes.
But all that said I still wanted to photograph the comets if I got the chance, clouds, rain and light pollution be damned, and planned my angles and positions from my rooftop everyday - morning and evening. Planning involved looking at the weather forecasts multiple times a day for the opportune moment, poring over various sky charts to gauge the position of the comets. This was a once in a lifetime opportunity and I was certainly going to try everything to get it.
Using apps like Star Walk 2 and Photopills to determine the shooting parameters as best as I could - low light, light pollution, preventing stars trailing, managing noise, shutter speeds, which lens to use for maximum intake of the little light there was etc. Constantly studying and monitoring the cloud cover on apps like Accuweather & Clear Outside and spending numerous 3am to 6am and 6pm to 9pm time windows on my rooftop and garden looking to the skies in the hope that they will clear.
I had done a very similar exercise for Comet Neowise and the photo below is of the Comet as I saw it from my rooftop in Hyderabad, a Bortle 9 Sky. More detail on the Blog.
Related Posts
