The Pelican Nebula - In search of HH-555

[steppenwolf]

In search of HH-555

The presence of the Moon this week has meant that Ha is again the natural filter choice for imaging and this time I wanted to experiment with using 2 x 2 binning with my QSI 683 CCD camera. Much has been written about the KAF 8300 sensor being unsuitable for binning yet in a previous brief test of my own, I hadn’t really seen a problem.

As the proud owner of a classic 1998 300bhp Subaru Impreza, the numbers 555 have a special meaning to me so, wishing to capture HH-555 in a little more detail than previous images of mine, 1800 second 2 x 2 binned exposures seemed like a worthwhile and fun experiment especially as it is lodged in one of my favourite objects, The Pelican Nebula.

Part of The Pelican Nebula in Ha

The location of the Herbig-Haro object within the Pelican Nebula (IC5070)

Image Stats

Mount: Mesu 200
Telescope: Sky-Watcher Esprit 150
Flattener: Sky-Watcher Esprit specific
Camera: QSI 683 WSG-8
Filter: Astrodon 3nm Ha
Subframes: 14 x 1800 sec bin 2x2 Ha
Integration: 7 hours
Control: CCD Commander
Capture: MaxIm DL
Calibration, Stacking and Deconvolution: PixInsight
Post-Processing: PhotoShop PS3

The same Ha data combined with an earlier colour image

Description

The jets emanating from this beautiful Herbig-Haro object can be found at the top of a dust and gas pillar at the back of the Pelican's 'neck' in IC5070, The Pelican Nebula in Cygnus. Often overshadowed somewhat by its near neighbour, NGC 7000, (The North America Nebula), from which it is separated by a large molecular cloud filled with dark dust, the Pelican is a delightful region of emission nebulosity. This nebula is of particular interest to astronomers as it hosts many regions of star-birth activity which leads us neatly to Herbig-Haro objects!

Herbig-Haro objects are small patches of nebulosity that are formed when the out-flowing jet from a ‘T-Tauri’ or ‘Herbig AeBe’ class star is in collision with a much slower moving interstellar medium. Herbig-Haro objects are, therefore, associated with regions of star-birth. The out-flowing ionized jets are aligned with the rotational axis of the star and are perpendicular to the proto-star's accretion disk which must be present for the process to kick-start. There are two distinct structures to a Herbig-Haro nebula, a ‘mach disk’ and a ‘bow shock’ generated by the jet. The jet itself decelerates in the mach disk and the interstellar medium accelerates in a bow shock. This process creates an enormous amount heat which in turn causes the nebula to emit radiation in the form of the light energy that we can observe. The importance of these jets in later planetary formation - always a hot topic - is that they stabilise the rapidly spinning star and its accretion disk by removing excess angular momentum.

Discovery

The story of Herbig-Haro objects starts in October 1852 when the English astronomer John Russell Hind discovered the variability of the star T Tauri in the constellation of Taurus in the same line of sight as the Hyades star cluster. This star was the progenitor for the class of variable stars known rather catchily as ‘T Tauri Stars’. We then move forward half a century when the American astronomer Sherburne Wesley Burnham was examining T-Tauri with the 36-inch refractor at the Lick Observatory and discovered a small region of nebulosity very close to the star. This small patch of nebulosity has the common name of ‘Burnham’s Nebula’. So, where do Herbig and Haro fit in? To the cataloguers go the spoils. These regions of nebulosity were not immediately recognised as a distinct type of emission nebula until the 1940s when George Howard Herbig, an American astronomer at the University of Hawaii Institute for Astronomy and the Spanish astronomer Guillermo Haro Barraza at the Tonantzintla Observatory in the Mexican state of Puebla started to research them independently. Subsequently, the two astronomers worked together to produce a catalogue of these nebulae which runs to several hundred entries. Burnham’s Nebula is catalogued as HH-255.

Location of The Pelican Nebula

 

[PhotoGav]

Very nice indeed Steve, showing what’s possible with the Esprit 150, some Ha and a bit of moonlight. The QSI has done very well even at 2x2. Great write up too, though HH-555, call it what you like, it is really the Rabbit’s Smile... turn your head 90 degrees counter clockwise and you will see!

[Laurin Dave]

Lovely image Steve and a most informative write  up. Been wondering what the "rabbits smile" was since I imaged this with my Esprit 150 5nm filter and ASI1600 a few weeks back. 

Dave

[teoria_del_big_bang]

Great image and a brilliant write up, many thanks for taking the time and for sharing it with us all .

Steve

[peter shah]

great shot...nice write up

[laser_jock99]

Good image and background info.

[gorann]

Looks more like a rat's smile to me but a superb image all the same! Esprit 150 is just such a great scope?

[SIDO]

Excellent!

[coatesg]

Very nicely done - you've also caught HH563 and HH564 just to the south west past the next "pillar" (somewhat less spectacular, but clearly visible)

[Rodd]

Nice--the image as well s the encyclopedic presentation.  

Rodd

[MartinB]

Looks great Steve, fitting tribute to the Subaru!  No idea how well the binning has worked with regard to resolution since you would need full size images, which is one big point in favour of binning.  In reality, how often do we present our images at full size other than to allow zooming in and pixel peeping?  Even with the moon up your background sky brightness probably wouldn't take you above read noise unbinned, even with 1800 secs and a 3nm filter.  Your read noise will be much lower when binned so 7 hours is a huge amount of exposure which shows in the depth of this image.  Binning also increases the dynamic range of course.  Maybe binned should be your default with the Esprit!

[steppenwolf]

On 29/09/2018 at 18:03, PhotoGav said:

Very nice indeed Steve, showing what’s possible with the Esprit 150, some Ha and a bit of moonlight. The QSI has done very well even at 2x2

Thanks, Gav - I love this telescope and although it isn't a universally popular mode, I do like mono images AND my productivity increases as I can image deeply under the Moon. I see the smile ?

On 29/09/2018 at 18:23, Laurin Dave said:

Lovely image Steve and a most informative write  up.

Thank you, Dave, enjoy your Esprit.

On 29/09/2018 at 19:21, teoria_del_big_bang said:

Great image and a brilliant write up, many thanks for taking the time and for sharing it with us all .

Thank you, Steve, pleased you like the image and write up.

On 29/09/2018 at 19:32, peter shah said:

great shot...nice write up

Thanks, Peter.

15 hours ago, laser_jock99 said:

Good image and background info.

Background info? The text or the background sky? - Just kidding, I'm pleased you like it.

12 hours ago, gorann said:

Looks more like a rat's smile to me but a superb image all the same! Esprit 150 is just such a great scope?

Thanks Göran, maybe it is a rat's smile after all! Yup, great 'scope

11 hours ago, SIDO said:

Excellent!

Thanks!

11 hours ago, coatesg said:

Very nicely done - you've also caught HH563 and HH564 just to the south west past the next "pillar" (somewhat less spectacular, but clearly visible)

Thank you for that observation, Graeme, I really must look into those as well. I could do with a decent copy of the HH catalogue.

11 hours ago, Rodd said:

Nice--the image as well s the encyclopedic presentation.  

Thank you, Rodd, I do like carrying out the research after I have captured an image - I'm like a sponge for knowledge these days, if only I had that thirst when I was at school ?

43 minutes ago, MartinB said:

Looks great Steve, fitting tribute to the Subaru! ..... In reality, how often do we present our images at full size other than to allow zooming in and pixel peeping? .........Your read noise will be much lower when binned so 7 hours is a huge amount of exposure which shows in the depth of this image.  Binning also increases the dynamic range of course.  Maybe binned should be your default with the Esprit!

Thanks, Martin and you are quite right of course, we rarely see our images at full size except when pixel peeping which ought to be an Olympic sport! There is a good argument for binning with this focal length and and pixel size as the sampling is 2.04 arcseconds per pixel which with my typical seeing is quite a good place to be. In my tests last year , the binning didn't appear to show any extra artefacts and the same applies to this image as well. Somewhere, I have some comparison images captured binned and unbinned - I will try and look them out. As far as I am concerned though, binning 2 x 2 works fine with my example of the KAF 8300 sensor although I don't have a set of qualitative values for how much deeper the binned images are over the native images.

Thank you all for your comments.

[tomato]

Late to this one, wonderfully detailed image and description, to continue the automotive theme, the Esprit is definitely hitting on all cylinders!

[steppenwolf]

On 03/10/2018 at 22:33, tomato said:

Late to this one, wonderfully detailed image and description, to continue the automotive theme, the Esprit is definitely hitting on all cylinders!

I'm pleased you like both image and text - the Esprit is indeed firing on all cylinders, possibly my best ever astronomy purchase to be honest.

[tomato]

Yes, I too am impressed with how this scope can produce a presentable result on total integration times measured in minutes rather than hours, although I am looking forward to when my 'grab and go' approach to AP will be in the past.

[swag72]

A super mono image Steve - What is there not to love?

I did an annotated HHH version of this area last year if you'd like me to post it up on the thread or PM it to you

[steppenwolf]

5 hours ago, swag72 said:

A super mono image Steve - What is there not to love?

I did an annotated HHH version of this area last year if you'd like me to post it up on the thread or PM it to you

Hi Sara, feel free to post it up here ?