SN 2023ixf was a bright supernova in the Pinwheel galaxy M 101 in constellation UMa. With maximum brightness of V~11.0 mag (end of May 2023) it was easily reachable whithin the Alpy600 spectrograph.
It needed good weather conditions for spectra recording. At start time of the spectroscopy session the object had an altitude of 77°, at the end it was at 54° a really comfortable position.
2023-05-26: First recording of a spectrum: 22:21 - 00:25 UT with the following conditions: mostly clear sky, moon (34%) at the beginning in 18° altitude, later below horizon, low humidity, average seeing, wind: light air, temperature: 15° C
2023-06-03: Second recording of a spectrum: 22:30 - 00:47 UT under good conditions: clear sky, full moon (100%) at the beginning in 16° altitude, later in 13° altitude, low humidity, good seeing, wind: calm, temperature: 15° C
2023-06-09: Third recording of a spectrum: 22:47 - 01:09 UT under very good conditions: clear sky, at the beginning no moon, later (60%) in 2° altitude, low humidity, good seeing, wind: calm, temperature: 16° C
2023-06-16: Fourth recording of a spectrum: 21:22 - 01:50 UT under good conditions: clear sky, no moon, low humidity, average seeing, wind: calm, temperature: 15° C
2023-06-24: Fifth recording of a spectrum: 21:03 - 01:46 UT under good conditions: clear sky, moon: (36%) at the beginning in 19° altitude, later below horizon, low humidity, good seeing, wind: calm, temperature: 15° C
2023-07-07: Sixth recording of a spectrum: 21:34 - 22:55 UT under average conditions: at the beginning clear sky, later cloudy, moon: at the beginning below horizon, later (73%) in 9° altitude, low humidity, average seeing, wind: calm, temperature: 18° C
2023-07-08: Seventh recording of a spectrum: 22:17 - 01:06 UT under average conditions: clear sky, moon: at the beginning below horizon, later (61%) in 26° altitude, low humidity, average seeing, wind: calm, temperature: 19° C
2023-05-21 22:09 - 22:26 UT, Roof Observatory Kaufering, 14" ACF teleskop on Taurus GM-60 mount, CCD camera: Moravian G2-8300FW, 3x3 Binning, L-filter, 42x60s; magnitude measured with Astrometrica: V=11.5 mag;
See SN 2023ixf at Latest Supernovae page for more information and images.
Spectra of this supernova:
2023-05-26 22:21 - 00:25 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 668196 (HD 122007), A3V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3710 Å) due to strong noise.
2023-06-03 22:30 - 00:47 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 67848 (HD 121489), A0V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3750 Å) due to strong noise.
2023-06-09 22:47 - 01:09 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 67848 (HD 121489), A0V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3710 Å) due to strong noise.
2023-06-16 21:22 - 01:50 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 67848 (HD 121489), A0V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3730 Å) due to strong noise.
2023-06-24 21:03 - 01:46 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 67848 (HD 121489), A0V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3730 Å) due to strong noise.
2023-07-07 21:34 - 22:55 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 67848 (HD 121489), A0V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3765 Å) due to strong noise.
2023-07-08 22:17 - 01:06 UT, Roof Observatory Kaufering,
Meade 14" ACF telescope on Taurus GM-60 mount, Astro Physics reducer CCDT67,
Alpy600 with guiding unit, CCD camera: Atik 428EX, guiding camera: ASI 120 MM; recording software: AstroArt, guiding software: PHD2
Wavelength calibration: Hg lines from energy saving lamp and Ne lines from flicker flame light bulbs,
instrumental response calibration: with reference star HIP 67848 (HD 121489), A0V, data reduction: with
Integrated Spectrographic Innovative Software from Christian Buil;
The spectrum has been cut at the near UV end (3760 Å) due to strong noise.
The classification with independent methods shows a type:IIP.
1) Classification with GELATO
(Padova-Asiago Supernova Group), see [1].
Spectrum from 2023-05-26 second best matches to SN 2008es (IIL pec) with an age of 12.5 d (Quality factor: 0.88); the age is too old.
Spectrum from 2023-06-03 second best matches to SN 2008es (IIL pec) with an age of 50.0 d (Quality factor: 1.13); the age is definitly wrong!
Spectrum from 2023-06-09 best matches to SN 2007od (IIP) with an age of 6.4 d (Quality factor: 1.65); the age is too young.
Spectrum from 2023-06-16 second best matches to SN 2007od (IIP) with an age of 13.5 d (Quality factor: 2.67); the age is too young.
Spectrum from 2023-06-24 best matches to SN 1995ad (IIP) with an age of 23.9 d (Quality factor: 3.18); the age is too young.
Spectrum from 2023-07-07 third best matches to SN 2007od (IIP) with an age of 46.4 d (Quality factor: 3.05); the age is good (50 days since explosion).
Spectrum from 2023-07-08 third best matches to SN 2007od (IIP) with an age of 46.4 d (Quality factor: 2.91); the age is al little bit too young (52 days since explosion).
2) Classification with SNID
(SuperNova IDentification), see [2].
Spectrum from 2023-05-26 best matches to SN 2004et (IIP) with an age of -2 d
The age of -2 is good estimated (around maximum brightness).
Spectrum from 2023-06-03 11th match to SN 1979C (IIL) with an age of 13 d - visually the best match.
The given age of 13 d is probably 5 days too late.
Spectrum from 2023-06-09 11th match to SN 2006Y (IIP) with an age of 27 d - visually the best match.
The given age of 27 d is probably 14 days too late.
Spectrum from 2023-06-16 best match to SN 2004ET (IIP) with an age of 10 d - visually the best match.
The given age of 10 d is probably 10 days too young.
Spectrum from 2023-06-24 best match to SN 2004ET (IIP) with an age of 10 d - visually the best match.
The given age of 10 d is probably 18 days too young.
Spectrum from 2023-07-07 sixth best match to SN 2006bp (IIP) with an age of 20 d - visually the best match.
The given age of 20 d is probably 21 days too young.
Spectrum from 2023-07-08 10th best match to SN 1992H (IIP) with an age of 44 d - visually the best match.
The given age of 44 d is quite good.
In both tools the red shift (z=0.000804) of host galaxy has been entered.
Note: The age in GELATO is given in days since explosion, wheras the age in SNID is given in days since maximum brightness.
The features in supernova spectra are all broad due to the very high ejection velocities, which typically are in excess of 10.000 km/s in young SN [3],[4]. A prominent feature in type IIP supernovae is a strong H-Alpha emission with a blue shifted absorption feature (P-Cygni profile). H-Beta and H-Gamma emission lines with blue shifted absorption features are also seen. He I emission with blue shifted absorption feature and Si II absorption are present [5]. A broad line of Na I D also appears. In spectra of older SN metal absorption lines of Fe, Ba, Ca, Ti, Sr and Sc are visible [5], [6].
Labeled spectrum 51 d after maximum light:
In the great papers from Dhungana et al. [5] and Bose et al. [6] are spectra with line identification of IIP SN 2013ej and 2013ab. I marked the lines in my spectrum accordingly, that could be clearly identified. Obviously the features have varying shifts. According to [6] the lines come from different layers or depths of expanding matter. The H-Alpha absorption has the largest shift, resp. the highest expansion velocity, it must come from the fastest and outermost shell. The Fe II lines are supposed to come from the expanding photospheric layer wheras the (weak) Sc II lines are formed at a even smaller radius. Limitation: In [6] they have detected Sc II lines only in spectra of SN age older than 77 d due to SNR. Hence my labeling may be wrong. In my spectrum from 2017-07-08 the supernova 2023ixf is younger.
PCP - P-Cygni profile
I measured the blue shifted absorption feature of H-Alpha in the following spectra:
In spectrum from 2023-06-09 the value of blue shift is 6361.8 Å against the rest wavelength at 6562.8 Å. This corresponds to a radial velocity of 8946.9 km/s of the ejected material (with correction of z=0.000804 from host galaxy M 101).
In spectrum from 2023-06-16 the value of blue shift is 6383.6 Å against the rest wavelength at 6562.8 Å. This corresponds to a radial velocity of 7950.4 km/s of the ejected material (with correction of z=0.000804 from host galaxy M 101).
In spectrum from 2023-06-24 the value of blue shift is 6408.8 Å against the rest wavelength at 6562.8 Å. This corresponds to a radial velocity of 6798.5 km/s of the ejected material (with correction of z=0.000804 from host galaxy M 101).
In spectrum from 2023-07-07 the value of blue shift is 6418.7 Å against the rest wavelength at 6562.8 Å. This corresponds to a radial velocity of 6345.9 km/s of the ejected material (with correction of z=0.000804 from host galaxy M 101).
In spectrum from 2023-07-08 the value of blue shift is 6418.4 Å against the rest wavelength at 6562.8 Å. This corresponds to a radial velocity of 6359.6 km/s of the ejected material (with correction of z=0.000804 from host galaxy M 101).
Spectral evolution of SN 2023ixf
In days since explosion.
The H-Alpha emission becomes stronger, the blue shift of absorption feature becomes less in wavelength and stronger in intensity, hence the ejected material is slower. There is a lack of light in the blue part in later spectrum.
