Confronto tra misurazioni di stelle doppie con Reduc e AstroimageJ

Autore: Cervoni Maurizio (Velletri -Roma) 1970maurizio@gmail.com

Abstract: Several shots were taken to measure double stars and to compare two software, Reduc and AstroimageJ. The results are quite similar, differing on average by less than a 0,2° for the angular separation, and even less for the angle of position (about 0,06°).

Sono state riprese 15 stelle doppie nel periodo giugno-agosto 2019 nelle costellazioni Hercules, Draco e Cygnus. L’intento era sia di verificare eventuali differenze nelle doppie riprese antecedentemente al 2017, sia di mettere a confronto due software: Reduc [1], nato esclusivamente per la misurazione delle stelle doppie e AstroimageJ [2]. Con Reduc è necessario acquisire molte immagini del target e della stella di calibrazione, in modo da ridurre l’errore e ottenere una media attendibile dei risultati; indispensabile risulta la conoscenza dell’orientamento della camera di ripresa, fattore che permette di determinare l’angolo di posizione della coppia. AstroimageJ ricava i risultati dalla risoluzione astrometrica (plate solving) delle foto riprese e non richiede la conoscenza dell’orientamento della CCD, quindi l’elaborazione risulta molto più veloce e agevole anche come aiuto nel centrare la stella esattamente sul centroide. Attrezzatura: per il seguente lavoro è stata impiegata la strumentazione dell’Associazione Tuscolana di astronomia (ATA) composta dal telescopio Meade ACF 35/3500; CCD Sbig ST8; montatura GM2000.
Conclusioni: nella tabella Risultati vengono riportate le misure ottenute con Reduc, e confrontate le differenze (O-C) con quelle riportate sul sito WDS (vedi tabella Doppie misurate).
Per quanto concerne invece le discordanze tra i due software utilizzati per elaborare i dati, ritengo che siano minime, nonostante usino algoritmi differenti per il calcolo. I dati similari ottenuti nei due programmi garantiscono una certa affidabilità delle misure ottenute. Per l’angolo di posizione ho trovato una differenza in media di 0.158°; ancora inferiore risulta lo scarto sulla separazione angolare, con una media di 0,062°. Il campione confrontato non è così ampio da avere una valenza statistica, infatti le riprese andrebbero ripetute su un numero di doppie molto più alto.
Una forte limitazione all’utilizzo di AstroimageJ è data dal fatto che il plate solving non funziona quando ci sono poche stelle nel campo di ripresa, situazione abbastanza frequente per chi segue questi target.

Riferimenti
[1] Reduc – http://astrosurf.com/hfosaf/
[2] AstroimageJ – https://www.astro.louisville.edu/software/astroimagej/
Stelle Doppie – https://www.stelledoppie.it/ (Gianluca Sordiglioni)
Duplice Sistema – http://duplicesistema.blogspot.com/ (Giuseppe Micello)

 

ROTATIONAL PERIOD DETERMINATION OF TWO MAIN BELT ASTEROID: (4807) NOBORU AND (1435) GARLENA

Angelo Tomassini, Maurizio Scardella,
Francesco Franceschini, Fernando Pierri
ATA (Associazione Tuscolana di Astronomia)
“F. Fuligni” Observatory    (MPC D06)
Via Lazio, 14 – Rocca di Papa (RM) – 00040 – ITALY

The observations of the analysed asteroids were carried out from F. Fuligni Observatory using a 0.35-m f/10 ACF telescope and SBIG ST8-XE CCD camera with Clear filter and from Franceschini’s equipment using a 9.25″ f/6.3 reflector telescope equipped with Atik 314L- CCD camera with Clear filter.  All images were dark and flat-field calibrated with Maxim DL. Differential photometry and period analysis performed using MPO Canopus (Warner, 2012).

(4807) Noboru. This inner main belt asteroid (discovered on January 10, 1991 by T. Kobayashi) has taken the name of Noboru Yamada (1950-1989), one of the greatest Japanese climbers. Its orbit ranges between 1.83 to 2.82 AU from the Sun. Our measurements have been taken from 18 December since 11 of January (4 sessions in total). The observations carried out from “F. Fuligni” Observatory and from Franceschini personal equipment, allowed to derive the synodic period of P = 4.00 ± 0.01 h with an amplitude of A =  0.18 mag (Figure 1).

(1435) Garlena. The second object observed during the period 06-22 of February in 4 sessions, is another main belt asteroid discovered on November 23, 1936 by K. Reinmuth at Heidelberg Observatory and named in honor of an acquaintance of the German astronomer W. Schaub. Our observations show a synodic period of P = 5.75 ± 0.01 h with an amplitude of A =  0.62 mag (Figure 2).

References

Warner, B.D. (2012). The MPO Software, Canopus version 10.4.1.9. Bdw Publishing, http://minorplanetobserver.com/

Warner, B.D. (2012). The MPO User Guide: A Companion Guide To The MPO Canopus/PhotoRed Reference Manual. BDW Publishing, Colorado Spring, CO.

Warner, B.D. (2018) “Lightcurve Photometry Opportunities: Oct-Dec 2018”. MPB 45-4.

Warner, B.D. (2019) “Lightcurve Photometry Opportunities: Jan-Mar 2019”. MPB 46-1.

Kenneth Zeigler, Tyler Barnhart, Armand Moser, Tatiana Rockafellow (2019) “CCD Photometric Obsevations of asteroids 2678 Avasaksa, 3769 Arhturmiller, 4807 Noboru, (7520) 1990 BV, and (14510) 1996 ES2”. MPB 46-2.

Daniel A. Klinglesmith III, Zackary Goodwrench (2019) “Etscorn  Lightcurves: January 2019 – April 2019”. MPB 46-3.

Figure 1. Lightcurve of 4807 Noboru. Period P = 4.00 ± 0.01 h with an amplitude A = 0.18 mag.

Figure 1. Lightcurve of 4807 Noboru. Period P = 4.00 ± 0.01 h with an amplitude A = 0.18 mag.

Figure 2.The lightcurve of 1435 Garlena. The period found is P = 5.75 ± 0.01h with an amplitude of A = 0.62 mag.

Acknowledgement

We would like to thank Simone Nodari and Samuele Piscitello for their help in taking the images and for the maintenance tasks of the ATA observatory instruments.

 

Periodo di rotazione di 3766 Magnusson

Angelo Tomassini, Maurizio Scardella, Francesco Franceschini
Fernando Pierri
Associazione Tuscolana di Astronomia (D06)
F. Fuligni Observatory
Via Lazio, 14 – località Pratoni del Vivaro – 00040
Rocca di Papa (RM) – ITALY

The inner main-belt asteroid (3677) Magnusson has been observed over several nights in the late 2018 summer in order to determine its synodic rotation period
and amplitude. Lightcurve analysis shows a synodic period P = 7.90 ± 0.01 h with an amplitude A = 0.89 mag.

The main-belt asteroid 3677 Magnusson has been selected from the listing of “Lightcurve Photometry Opportunities” July-September (Warner, 2018). This asteroid, belonging to the Flora family, has been discovered by Edward Bowell in 1984 and is named in honor of Per Magnusson, a planetary astronomer at
Uppsala Observatory. All the observations were carried out from F. Fuligni Observatory, using a 0.35-m f/10 Advanced Coma Free telescope and SBIG ST8-XE CCD camera with Bessel R filter and from Franceschini’s equipment using a 9.25″ f/6.3 reflector telescope equipped with Atik 314L- CCD camera with Astrodon R
filter. All images were calibrated with dark frames. Differential photometry and period analysis was done using MPO Canopus (Warner, 2012).

The derived synodic period was P = 7.90 ± 0.01 h (Fig.1) with an amplitude of A = 0.89 mag.

References
Harris, A.W., Young, J.W., Scaltriti, F., Zappala, V. (1984).
“Lightcurves and phase relations of the asteroids 82 Alkmene and 444 Gyptis.” Icarus 57, 251-258.
Warner, B.D. (2012). MPO Software, Canopus version 10.4.1.9.
Bdw Publishing, http://minorplanetobserver.com/
Warner, B.D. (2018). “Lightcurve Photometry Opportunities 2018 July-September.” MPB 45-3.

Figure 1.The lightcurve of (3677) Magnusson with a period of 7.90 ± 0.01 h and an amplitude of 0.89 mag.

 

Calcolo del periodo di rotazione di 16852 Nuredduna

Angelo Tomassini, Maurizio Scardella, Francesco Franceschini
ATA (Associazione Tuscolana di Astronomia)
“F. Fuligni” Observatory (MPC code D06)
Via Lazio, 14 – Rocca di Papa (RM) – 00040 – ITALY

The main-belt asteroid (16852) Nuredduna, was
observed between October and December 2017. The
synodic period is 6.3 ± 0.1 h.
Discovered in June 1995 at Steward Observatory, (16852)
Nuredduna was selected for observation from the “Lightcurve
Photometry Opportunities: Oct-Dec 2017” (Warner, 2017).
The observations of this main-belt asteroid lasted five nights
between October and December 2017. The observations were
carried out from F. Fuligni Observatory using a 0.35-m f/10 ACF
telescope and SBIG ST8-XE CCD camera with Bessel clear filter
and by Francesco Franceschini using a 9.25″ f/6.3 reflector
telescope equipped with Atik 314L+ CCD camera unfiltered. All
images were dark and flat-field calibrated with Maxim DL. The
lightcurve analysis has been performed with a differential
photometry technique extrapolating the best polynomial of
approximation of the observations, using the program MPO
Canopus (Warner, 2012). The resulting synodic period is found to
be P = 6.3 ± 0.1 h with an amplitude of A = 0.41 mag (Figure 1).

                                                      Fig. 1 Curva di luce dell’asteroide 16852 Nuredduna

                                Acknowledgement
We would like to thank Fernando Pierri, Simone Nodari and
Samuele Piscitello for help in taking image frames and
maintenance of the ATA observatory instruments.

ROTATIONAL PERIOD DETERMINATION OF TWO MARS CROSSING, A MAIN BELT ASTEROID AND A PHA: (14309) DEFOY, (56116) 1999 CZ7, (5813) EIZABURO AND (3122) FLORENCE

Angelo Tomassini, Maurizio Scardella,
Francesco Franceschini, Fernando Pierri
ATA (Associazione Tuscolana di Astronomia)
“F. Fuligni” Observatory (MPC D06)
Via Lazio, 14 – Rocca di Papa (RM) – 00040 – ITALY

The main-belt asteroids (5813) Eizaburo and two Mars crossing minor bodies, (14309) Defoy and (56116) 1999 CZ7, have been observed over several nights throughout 2017 March-September in order to determine their synodic rotational period. We also took the opportunity of the (3122) Florence close passage with the Earth in September-October to find its lightcurve.

The observations of the analysed asteroids were carried out from F. Fuligni Observatory using a 0.35-m f/10 ACF telescope and SBIG ST8-XE CCD camera with Clear filter and from Franceschini’s equipment using a 9.25″ f/6.3 reflector telescope equipped with Atik 314L- CCD camera with Clear filter.  All images were dark and flat-field calibrated with Maxim DL. Differential photometry and period analysis was done using MPO Canopus (Warner, 2012).

3122 Florence. This asteroid, discovered from the Siding Spring observatory at the beginning of the ‘80s, belongs to the Amor family and being potentially dangerous for the Earth is also classified as PHA. A diameter of 4.9 Km makes it one of the biggest PHA known. Its orbit, resonant with the Earth, brings this big object close to our planet every 40 years and the 2017 passage has been the closest for at least the next 160 years. During this close flyby a radar observation has shown the presence of 2 natural moons with diameter of around 180-240m and 300-360m. Our measurements have been taken since the first days of September (8 sessions in total) but only the last observations have been used for the lightcurve, fitting these data more coherently with the known asteroid properties. The synodic period found has been of P = 2.36 ± 0.01 h and an amplitude of A = 0.14 mag (Figure 1)

5813 Eizaburo. This Main Belt Asteroid (also called 1988 VL) has been discovered in 1988 by Takuo Kojima. Its semi-major axis is 2.60 AU and the inclination is 11.24º. The observations lasted more than one month, from the Franceschini’s equipment and from the “F. Fuligni” Observatory have confirmed for this MBA a synodic period of P = 2.93 ± 0.01 h and an amplitude of A = 0.26 mag (Figure 2).

14309 Defoy.  Discovered by J. Palisa in 1908 in Vienna, this asteroid is a Mars Crossing Asteroid with a semi-major axis of 2.60 AU and 0.447 as eccentricity. The observations carried out from “F. Fuligni” Observatory and from Francesco Franceschini during four nights in June 2017 allowed us to derive the synodic period of P = 3.4 ± 0.1 h with an amplitude of A = 0.16 mag (Figure 3).

  (56116) 1999 CZ7.  Discovered in 1999 at Socorro (New Mexico), this minor body is classified as Mars Crossing Asteroid, having a perihelion (1.6653 AU) barely lower than the Mars aphelion (1.666 AU). Its aphelion is about 2.97 AU while the orbital period is 3.53 years. The observations of this asteroid have been carried out by our team during March-April 2017 over four nights. The resulting lightcurve has a synodic period of P = 3.12 ± 0.01 h and amplitude 0.27 mag (Figure 4).

 Acknowledgement
We would like to thank Simone Nodari and Samuele Piscitello for their help in taking the images and for the maintenance tasks of the ATA observatory instruments.

References
Warner, B.D. (2012). The MPO Software, Canopus version 10.4.1.9. Bdw Publishing, http://minorplanetobserver.com/
Warner, B.D. (2012). The MPO User Guide: A Companion Guide To The MPO Canopus/PhotoRed Reference Manual. BDW Publishing, Colorado Spring, CO.
Warner, B.D. (2017) “Lightcurve Photometry Opportunities: Jan-Mar 2017”. MPC 44-1.
Warner, B.D. (2017) “Lightcurve Photometry Opportunities: April-June 2017”. MPC 44-2.
http://www.MinorPlanet.info/PHP/call_OppLCDBQuery.php

 

 

 

Il bolide del 13 agosto 2017

Molto probabilmente nessuno avrà potuto beneficiare dello spettacolo che avrebbe offerto il bolide che ha attraversato  l’atmosfera sopra le nostre teste il 13 di agosto in quanto era pieno giorno  e la luce del Sole, molto intensa a quell’ora, ha sicuramente offuscato quella emessa dal meteoroide.

Per “bolide” s’intende una meteora molto luminosa, più luminosa del pianeta Venere, e quindi molto spettacolare quando appare nel cielo scuro della notte.

Ma se nulla poteva l’occhio nudo , il fenomeno non è passato inosservato alla nostra stazione per radio meteore che era vigile ed attenta in quanto acquisisce in continuo i segnali radio riflessi dalla scia delle meteore e quindi ha registrato la sua “eco”.

La foto mostra la traccia radio registrata dalla nostra stazione per “radio meteore” del bolide apparso nei nostri cieli il 13 di agosto alle 12.22 circa di TU. La traccia dura più di un minuto. Se la “breccola cosmica” avesse ritardato di qualche ora ad impattare contro la nostra atmosfera ci sarebbe stato uno spettacolo pirotecnico non indifferente.

Dal momento che è impossibile in queste condizioni calcolare l’orbita di questo meteoroide non sappiamo a quale cometa o asteroide associarlo. Ad ogni modo possiamo ragionevolmente ipotizzare che appartenga allo sciame meteorico delle “perseidi” sia in quanto coincidente appieno col periodo di massima osservazione di questo sciame meteorico e sia perché a questo sciame è associato il maggior numero di bolidi osservabili.

Quindi non potendo calcolare una traiettoria del bolide, nemmeno possiamo tentare un calcolo di un eventuale impatto col suolo anche se quasi sicuramente il meteoride si sarà completamente volatilizzato in bassa atmosfera. Molto probabilmente il suo pulviscolo residuo dopo essere stato trascinato dai venti in quota avrà raggiunto il suolo terrestre posandosi delicatamente chissà dove…

 

 

Maurizio Scardella
Responsabile Gruppo Ricerca ATA

P.S.
Un doveroso ringraziamento ai Soci Fernado Pierri, Samuele Piscitello e Simone Nodari per l’attenta e accurata gestione tecnica della stazione radio meteore dell’ATA.

Traccia radar lasciata dal meteoroide registrata alla stazione radiometeore ATA

 

Calcolato il periodo di rotazione di (703) Noemi

Lorenzo Franco Balzaretto Observatory (A81), Rome, ITALY lor_franco@libero.it

Maurizio Scardella, Angelo Tomassini,
Francesco Franceschini, Fernando Pierri
Osservatorio Astronomico “F. Fuligni” (D06)
Via Lazio 14, 00040 Rocca di Papa (RM), ITALY

Alessandro Marchini
Astronomical Observatory, DSFTA – University of Siena (K54)
Via Roma 56, 53100 – Siena, ITALY
(Received: 2017 Apr 5)

Collaborative lightcurve photometry observations of
main-belt asteroid 703 Noemi were made over 16 nights
in 2016 November thru 2017 January. The resulting
synodic rotation period is 200 ± 1 h, amplitude 0.62 ±
0.10 mag, HR = 12.24 ± 0.12 and GR = 0.16 ± 0.10.

The main-belt asteroid 703 Noemi was discovered on 1910 October 3 by J. Palisa at Vienna. The primary orbital elements are  a = 2.175 AU, e = 0.138, and i = 2.46°. Its absolute magnitude is H = 12.5 (JPL, 2017). The NEOWISE survey (Nugent et al., 2016) used a value of 12.70 to find a diameter of D = 9.85 ± 1.42 km. The gives an optical albedo of pV = 0.19 ± 0.10. CCD photometric observations were made over 16 nights from 2016 November 15 to 2017 January 29 at the Balzaretto Observatory (A81), Fuligni Observatory, and the DSFTA Observatory (DSFTA, 2017) using the instrumentation described in Table I.

Data processing and analysis were done at the Balzaretto Observatory with MPO Canopus (Warner, 2016). All the images, acquired with clear-filter, were calibrated with dark and flat frames and converted to the Cousins-R magnitudes using solar colored field stars from CMC15 catalogue (VizieR, 2014) by the relationship R = r´ – 0.22 (Dymock and Miles, 2009). No offset adjustment was applied to the lightcurves. The period analysis shows a bimodal solution for P = 200 ± 1 hours and amplitude A = 0.62 ± 0.10 magnitudes.

The absolute magnitude H (R-band) and slope parameter G were found using the H-G Calculator function of MPO Canopus. For each lightcurve the average R mag was measured removing the rotational effects, using a Fourier fit model (Buchheim, 2010). We found H (R-band) = 12.24 ± 0.12 mag, G = 0.16 ± 0.10. For 703 Noemi, the taxonomic class and the color index are unknown. We assume it is S-type asteroid, according to SMASSII taxonomic class distribution vs semi-major axis (Bus and Binzel, 2002) with a color index V-R = 0.49 ± 0.05 (Shevchenko and Lupishko, 1998). We then derive H = 12.73 ± 0.13, close to the H = 12.7 listed by Nugent et al. (2016).

Observatory            Telescope,                   CCD              Exp (s)

Balzaretto (A81)- 0.20-m f/5.5          SCT SBIG ST7xme         420

Fuligni (D06)- 0.35-m f/10                 SCT SBIG ST8-xe            120

DSFTA (K54)- 0.30-m f/5.6 MCT   SBIG STL-6303e (2×2)    300

Table II. Observing Instrumentation. SCT: Schmidt-Cassegrain Telescope, MCT: Maksutov-Cassegrain Telescope.

References

Bus S.J., Binzel R.P. (2002). “Phase II of the Small Main-Belt Asteroid Spectroscopic Survey – A Feature-Based Taxonomy.Icarus 158, 146-177.

DSFTA (2017). Dipartimento di Scienze Fisiche, della Terra e dell’Ambiente, University of Siena – Astronomical Observatory. https://www.dsfta.unisi.it/en/department/sciencemuseums/astronomical-observatory

Dymock, R., Miles, R. (2009). “A method for determining the V magnitude of asteroids from CCD images.” J. Br. Astron. Assoc. 119, 149-156.

Harris, A.W., Young, J.W., Scaltriti, F., Zappala, V. (1984). “Lightcurves and phase relations of the asteroids 82 Alkmene and 444 Gyptis.” Icarus 57, 251-258.

JPL (2017). Small-Body Database Browser. http://ssd.jpl.nasa.gov/sbdb.cgi#top Nugent, C.R., Mainzer, A., Bauer, J., Cutri, R.M., Kramer, E.A., Grav, T., Masiero, J., Sonnett, S., Wright, E.L. (2016).

“NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos.” Astron. J. 152, A63.

Shevchenko V.G., Lupishko D.F. (1998). “Optical properties of Asteroids from Photometric Data.” Solar System Research 32, 220-232.

VizieR (2014). http://vizier.u-strasbg.fr/viz-bin/VizieR.

Warner, B.D. (2016). MPO Software, MPO Canopus v10.7.7.0.

Bdw Publishing. http://minorplanetobserver.com