The Pleiades | M45

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The Pleiades

M45 • Open star cluster • Taurus • 440 light-years from Earth

🗓️
Dec ‘21 – Jan ‘22

The Pleiades M45 in Taurus, imaged from a light-polluted city

Overview

The Pleiades, also known as M45, is a bright open star cluster located around 440 light-years from Earth in the constellation Taurus. It’s made up of hot, young stars that are currently passing through a cloud of interstellar gas and dust. Rather than emitting light itself, this dust reflects the starlight, producing the distinctive blue glow that makes the Pleiades one of the most recognisable and visually striking targets in astrophotography, and a prime object to image from light-polluted skies.

Background

The Pleiades has been on my hit-list for a while, and so with the arrival of winter I decided its time had come. Being a broadband target, I didn’t use my faithful Optolong L-eXtreme filter. I rely on long integration times to brute force my way through light pollution and obtain a good signal-to-noise ratio.

Framed astrophoto taken from a light-polluted city, available to buy as a fine art print

Explore the field

1.0×
Objects in this field 26 objects
PleiadesM 45
Open clusterAlso catalogued as Mel 22 · LBN 770 · LBN 772 · Cr 42
Alcyoneη Tau
StarAlso catalogued as 25 Tau · HR 1165 · HD 23630 · HIP 17702
B7III · Double (STFA 8AB) 117.6″ at 291°, companion 6.27 mag
Electra17 Tau
StarAlso catalogued as HR 1142 · HD 23302 · HIP 17499
B6III
Atlas27 Tau
StarAlso catalogued as HR 1178 · HD 23850 · HIP 17847
B8III
Maia20 Tau
StarAlso catalogued as HR 1149 · HD 23408 · HIP 17573
B8III
Merope23 Tau
StarAlso catalogued as V971 Tau · HR 1156 · HD 23480 · HIP 17608
B6IV · β Cep variable 4.18–4.19 mag
Celaeno16 Tau
StarAlso catalogued as HR 1140 · HD 23288 · HIP 17489
B7IV
Taygetaq Tau
StarAlso catalogued as 19 Tau · HR 1145 · HD 23338 · HIP 17531
B6V
Asterope21 Tau
StarAlso catalogued as HR 1151 · HD 23432 · HIP 17579
B8V · Double (HJL 1026AB) 149.6″ at 130°, companion 6.42 mag
Pleione28 Tau
Variable starAlso catalogued as BU Tau · HR 1180 · HD 23862 · HIP 17851
B7p · γ Cas variable 4.77–5.50 mag
Merope NebulaNGC 1435
Reflection nebulaAlso catalogued as vdB 22 · Ced 19j
Maia NebulaNGC 1432
Reflection nebulaAlso catalogued as LBN 771 · vdB 21 · Ced 19f
Ced 19g
Reflection nebula
Ced 19e
Reflection nebula
Ced 19c
Reflection nebula
Ced 19h
Reflection nebula
18 Tau
StarAlso catalogued as HR 1144 · HD 23324 · HIP 17527
B8V
Ced 19o
Reflection nebula
22 Tau
StarAlso catalogued as HR 1152 · HD 23441 · HIP 17588
A0Vn
26 Tau
StarAlso catalogued as HD 23822 · HIP 17832
F0
Ced 19k
Reflection nebula
LBN 776
Reflection nebula
Barnard's Merope NebulaIC 349
Reflection nebulaAlso catalogued as Ced 19i
IC 1990
NebulaAlso catalogued as Ced 19m
vdB 20
Reflection nebulaAlso catalogued as Ced 19d
vdB 23
Reflection nebulaAlso catalogued as Ced 19l
About the labels and credits

Positions and outlines are calculated from a plate solution of this photograph. Outlines are catalogue guides and may not follow every visible filament. Additional catalogue objects may be faint or indistinct in this exposure.

Plate solving and annotation data: SkySolver, by Dominik Sito. Stars: Gaia DR3 and Hipparcos (ESA). Deep-sky data: OpenNGC © Mattia Verga (CC BY-SA 4.0), SIMBAD and VizieR (CDS). Names: Wikipedia (CC BY-SA 4.0) and IAU WGSN. Catalogue overlay adaptations, including styling and selected display names, are shared under CC BY-SA 4.0. Photograph © Lee Pullen.

Science

My favourite part of the Pleiades is the Merope Nebula. It’s so-named because it’s the nebula surrounding the star Merope, although it also has an official name: NGC 1435.

The nebula itself is the result of fine grains of dust surrounding the star reflecting light, giving it soft blueish hue. The wisps are produced by a few processes:

  1. Dust particles clumping together;
  2. Blue light being scattered the most, making areas with smaller dust grains look lighter;
  3. Radiation and stellar winds from nearby stars carving out filaments;
  4. Motion within the nebula twisting and stretching filaments over time.

Imaging details

Date

Dec 2021 – Jan 2022

Location

Bristol, UK (Bortle 8)

Telescope

Askar FRA400

Camera

ZWO ASI 2600MC Pro

Mount

Orion Sirius EQ-G

Guiding

WO 32mm + ZWO ASI 120MM Mini

Control

ASIAIR Plus

Software

PixInsight, Lightroom

Image by

Lee Pullen

Filter

Channels

Exposure

No filter

RGB

660 × 2-minutes

22 hours

Imaging details

Date
Dec 2021 – Jan 2022

Location
Bristol, UK (Bortle 8)

Telescope
Askar FRA400

Camera
ZWO ASI 2600MC Pro

Mount
Orion Sirius EQ-G

Guiding
WO 32mm + ZWO ASI 120MM Mini

Control
ASIAIR Plus

Software
PixInsight, Lightroom

Image by
Lee Pullen

Filters

No filter
RGB
660 × 2-minutes

Total exposure: 22 hours

Kit list

This is the equipment I used to capture the image.
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Guidescope: William Optics 32mm Slide-Base Uniguide
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Buy from Astroshop.eu
Buy from High Point Scientific

Processing

For this image I conducted some experiments about stretching the data in PixInsight. Normally I’ll use EZ Soft Stretch or simply apply the STF function to HistogramTransformation, but I’d come across a Stargazers Lounge post about how some keen astroimagers have made a new process, called Generalised Hyperbolic Stretch (GHS). It’s quite complex to use.

Here’s my data stretched using three different methods:

The first two methods produced a fine result, but GHS did a better job of keeping the stars nice and tight, while bringing out more nebulosity. So, I kept the GHS version and went on to fully edit it. GHS has got a lot of potential, and I plan to use it for future images too; and maybe even re-edit some old data using it as well.

The rest of the processing was fairly straightforward. I did a little bit of DarkStructureEnhance and a few other tweaks in PixInsight. I tried to use StarNet to remove the stars, with a mind to process them separately to the nebulosity, but too many artifacts remained. Happily, the GHS stretch controlled the stars so effectively that I could actually use Topaz DeNoise AI on the whole image, including stars, and it worked nicely. (Normally Topaz DeNoise AI doesn’t handle stars well, so I just use it on starless versions, then add the stars back in later).

Then it was into Lightroom for some tweaks, and that was pretty much it.

Example astrophotography image promoting one-to-one online astrophotography masterclasses

Example source data

Here’s an example single subframe and freshly integrated stack, just with simple stretches applied.

Seestar S50 image

This photo of the Pleiades was taken using my Seestar S50 telescope.






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9 thoughts on “The Pleiades | M45”

  1. Tony Alonso says:

    A wall canvas worthy picture. One of my favorite targets and I absolutely love the color that you brought out on this target. One that I am anxiously excited for when my new rig comes in.

    I’m curious of the cropping you used. Did you use dynamic crop, Pixinsight? Beautiful target and beautiful photo.

    Reply
    1. Lee says:

      Thanks, I do actually have this one printed and framed on a wall! I always use DynamicCrop as the first stage of processing, but only to take a few pixels off each edge, in case there are any stacking artefacts. The next time I do any cropping is as the final stage of processing, before exporting the image.

      Reply
  2. Kurt says:

    Thanks for the insight on how to get the nebulosity from a polluted site, I did attempt this last winter from London but to no avail in capturing any nebulosity. But that was before I understood the frequencies of reflection nebulae are usually filtered out when using multiband or general pollution filters. I will attempt again this winter without any filters and as much exposure time as possible. I assume I should avoid this target on moonlit nights as well.

    I am enjoying your site, some very helpful information here. Thank you for this and some great images.

    Reply
    1. Lee says:

      Thanks Kurt! I actually image regardless of what the Moon’s doing. New Moon, Full Moon, it makes no difference to me. If the skies are clear, I’ll be collecting data. Good processing skills using software like PixInsight make all the difference! And for reference, most of the data used in this Pleiades photo was obtained with a bright Moon very nearby in the sky.

      Reply
  3. Simon Newman says:

    Just found your website Lee, great info here! I too image here from Bristol, near Henleaze so I guess Bortle 6.5 ish. I’m planning to image Pleiades next clear nights with my latest setup (125mm APO f5.9). Last time I used my skytech l-pro max lp filter, but dealing with the halos was a pita on this target, so will try without! I agree with integration time, I always try to get close to 10hrs min on targets. Cheers.

    Reply
    1. Lee says:

      Oh wow, you’re only a 20-minute drive from me – we’re practically neighbours! Good luck with your image, I’d be interested to see the end result. I’m tempted to give it another go with my new telescope too…

      Reply
  4. Alan Sanders says:

    On your ASI2600mc camera, did you use 0 gain or 100 gain as you didn’t use filters.
    Some Cloudynights posts say to use 0 gain for broadband objects from a light polluted area, while others use 100 gain for every object.
    FYI, I just received my ASI2600mc a few days ago and it’s been cloudy since. I’m probably going to try 0 gain on some galaxies and globular clusters from my Bortle 8 location just to see. Would you recommend 120 exposures as a start for Bortle 8 skies or would this oversaturate the stars?

    Reply
    1. Lee says:

      I use gain 100 and 120-second exposures for everything. It’s worked well so far! I guess I may need to reduce the subframe length if imaging something with lots of very bright stars, like The Pleiades, using my Askar 130PHQ, because it just collects to much light.

      Reply

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