Quasars around M98

20mnn exposure (L:4x300s)
Acquired on the 17th of March 2020 with 8″ ONTC


Setup: TS ONTC 200/800, 2″ Feathertouch, AZ-EQ6, QHY163m gain=100, OAG-M, QHYCFW2-M, AstroLink 4 mini. Software: APT, Stellarium, PHD2

This image is a quick capture part of a field already imaged in 2019 with Samyang 135mm lens. At this time, I was very surprised of detecting a quasar with a redshift of 3! Let’s see now what will be detected at 800mm of focal…

Location

The field of view of this image is located in Coma Berenis constellation, east of Denebola.

Virgo cluster location – Stellarium screen capture

As mentioned above, this field of view is contained inside a wider field acquired in 2019 with a Samyang 135mm lens:

Virgo cluster captured at 135mm. M98 capture at 800mm (top-right)

Deep sky objects

M98 is the main galaxy on this image. This is an intermediate spiral of apparent magnitude 11 located at 44 million light years. M98 is member of Virgo galaxy cluster like most of the large galaxies visible on the image above.

South of M98 lies NGC4186, a spiral galaxy of mag 13.8 located at about 360 million light years. 

On the bottom of the image figure also 2 IC objects:

  • IC3049, an irregular magellanic galaxy of mag 14.7 distante of 111 million light years (bottom center)
  • IC3065, an elliptical dwarf galaxy of mag 13.6 located at 56 million light years (bottom center)

All others objects are much fainter and are identified as PGC. See annotated image below:

M98 galaxy and co – Pixinsight annotations

Let’s now look at quasars… 🙂

Quasars

To identify quasars, I used Aladin software to extract objects data from the field of the image. Then I solved my image under Pixinsight and annotated it with a custom catalog containing the quasars found among the extracted data.

The image below is annotated with quasars references and magnitudes in g (AB) SDSS band:

Quasars arround M98 galaxy – Pixinsight annotations

And the image below mentions redshift for each quasar:

Quasars arround M98 galaxy – Pixinsight annotations

The table hereunder lists quasars magnitudes in several bands as well as their redshifts. One column mentions also whether quasars are detected or not on the image. Detection looks possible up to mag 21 in g (AB) SDSS band!

NAMEDetectedV (Visual)g (AB) SDSS greenr (AB) SDSS redRedshift
LBQS 1210+1507Yes17.66117.5811.61525
LBQS 1212+1445Yes17.917.93717.5321.62708
2MASS J12152958+1428412Yes18.3818.08718.0860.40266
LBQS 1209+1524Yes18.318.21318.0143.064455
2MASS J12142644+1438430Yes18.3818.34617.7660.50167
2MASS J12151058+1428342Yes 18.56918.4442.580123
SDSS J121505.43+145549.4Yes19.1218.83618.8551.64868
SDSS J121431.87+150438.2Yes19.2718.90118.6080.30132
LBQS 1213+1535Yes18.9619.06218.9081.39263
SDSS J121435.17+150400.4Yes19.3819.16818.931.23359
HVCS 311Yes19.3419.20718.9221.889859
SDSS J121302.07+143310.4Yes19.7419.45719.4561.79532
SDSS J121211.52+145615.2Yes19.6719.4819.3251.4844
1RXS J121315.0+144415Yes19.6319.66719.5370.7164
SDSS J121205.30+152005.8Yes20.0119.78419.7122.148511
SDSS J121451.59+144042.8Yes 19.9219.6752.433529
SDSS J121528.60+143952.6Yes 20.11320.0192.39856
SDSS J121513.24+151114.4Yes 20.25720.142.978001
SDSS J121243.53+142537.0No 20.37420.2732.234359
SDSS J121321.90+142441.3Yes 20.42320.4922.4104
SDSS J121339.16+142738.6Yes 20.5420.1192.420823
SDSS J121535.02+145653.3Yes 20.82320.6882.452138
SDSS J121329.51+142621.8Yes 20.94320.9142.362041
SDSS J121434.21+143641.3Yes 20.94820.4961.016425
SDSS J121537.55+150755.6Yes 20.96320.8241.390774
SDSS J121500.06+151950.5Yes 20.99920.8360.8062
SDSS J121432.80+152104.5No 21.07420.6793.307738
SDSS J121305.13+145530.1No 21.18921.060.8266
SDSS J121424.27+144404.9No 21.5621.2972.371571
SDSS J121209.11+145021.0No 21.73721.5953.0841
SDSS J121352.77+152034.4No 21.76721.3862.5259
SDSS J121421.86+151449.4No 21.84521.7862.219281
SDSS J121257.09+151508.3No 22.05621.7363.177655

LBQS 1209+1524 quasar

LBQS 1209+1524 is one of the quasars that was visible on the image captured one year ago with Samyang 135mm. This quasar has a redshift of 3.06 which indicates that the photons coming from it have travelled 11.5 billion years before hitting the camera CMOS sensor!

Usage of 8″ Newton confirms the detection. See image comparison below:

135mm vs 800mm focal length – LBQS 1209+1524 quasar

Conclusion

Increasing focal is obviously a big plus when it is matter to detect faint objects like quasars. For this present case,  800mm of focal lenght allows reaching mag 21 wheareas 135mm focal lenght was limited to mag 18.5. This longer focal length allows capturing LBQS 1209+1524 (mag 18.5) with a serious margin. And this is a long list of quasars which is now detected on a much narrower field.

Nevertheless, there is room for improvements with this 800mm focal length. Increasing unitary exposure (from 300s to 600s) and number of shoots will help to enhance detection.  Improving collimation and tracking will also help as well…

Leave a Reply

Your email address will not be published. Required fields are marked *