DaveGee
17-05-2015, 02:04 PM
It is not often that we have 3 high quality asteroid predictions that are observable from the Australia in the one month. The predictions for June 2015 have 3 such events, the first time that I can remember.
First off, let us define what is a high quality asteroid prediction, and in no particular order the attributes are;
- Reasonably bright star – a star brighter than mag. 12 is considered helpful.
- Asteroid fainter than star – it always helps to have the asteroid fainter than the star because then the magnitude drop when the even occurs is large, and this makes the event easier to see. In the case of the three events, all have mag.-drop of 2 or more.
- Event duration grater than 2 seconds – this helps to distinguish atmospheric scintillation from a real event.
- Error in time less than 5 seconds – this helps because we know with certainty that the event will occur at a certain time and we don’t have to watch the star for minutes at a time.
- IOTA Rank greater than 90 – IOTA ranks all event on a scale up to 100, where an event of 100 means that if an observer is sited between the bold path lines shown on the map, then they almost certainly will see the event.
- The event has extremely high value because the data obtained from the observations will directly aid space exploration. The 29th June Pluto event falls into this category. More on this later.
Lets discuss the events in detail. (refer to the Occult prediction maps).
5th June : (212) Medea occults TYC 0604-1157
This event occurs at 19:04:22 UT = 5:04:22 am on Saturday morning. The star is mag. 11 and the asteroid is mag. 14, so the mag.-drop is 3.1, making this easy for visual observers.
The southern limit crosses Sydney CBD, so any sites to the north-west, like Linden Observatory will benefit with greater event certainty.
The star and asteroid will be at alt. of 32° and az. of 52° at event time.
Steve Preston (of IOTA) has sourced the star position from the URAT1 catalogue, so we can be assured that the star position coordinates are the best available.
19th June : (420) Berthholda occults TYC 628-01716
This event occurs at 14:33:57 UT
= 12:33:57 am on Saturday morning. The star is mag. 11.6 and the asteroid is mag. 13.4, so the mag. drop is 2.0, and it is still in the realm of the visual observer.
The path is centred on Sutherland, and extends from Gosford to Moss Vale, so anywhere between those limits will see the event.
The star and asteroid will be at alt. of 74° and az. of 14° at event time.
Steve Preston (of IOTA) has sourced the star position from the URAT1 catalogue, so we can be assured that the star position coordinates are the best available.
29th June : Pluto Occults 4 UCAC 347-165728
This event occurs at 16:48:40 UT
= 2:48:40 am on Tuesday morning. The star is mag. 12 and the Dwarf planet is mag. 14, so the mag. drop is 2.2, and it is still in the realm of the visual observer, however the disappearance and reappearance events will be gradual, taking many seconds to occur, due to Pluto’s atmosphere.
The predicted path, obtained using the UCAC4 catalogue and the Pluto DE432 ephemeris, covers almost all of Australia, however we expect updates from The RIO Group (Felipe Braga Ribas et al) leading up to the event. The RIO Group perform precise astronomy on the target star and Pluto and produce high quality predictions.
Any positive observations from this event could benefit the New Horizons flyby.
Marc Buie of The Southwest Research Institute writes;
It's (the occultation) going to be a very important with its occurrence so close to the New Horizons flyby and it's own occultation experiments. It's also nice that the star is bright (and red).
One goal for this event will be to go for extra density coverage on the central flash if that part of the shadow is accessible over land.
This prediction work, when completed, will be distributed to everyone with any interest in this event. I expect Bruno and Felipe will be crucial to getting the word out.
I wish I could be in the field with everyone to observe this for myself but I'll be tied up in Baltimore with all the activities surrounding the New Horizons encounter with Pluto. I'm on the hazard team that is on the lookout for dangerous stuff on the way in. It's going to be a crazy-busy but exciting time.
--Marc
So I encourage all observers to monitor these three events. I have indicated that all three events are observable visually (with telescopes 8” or larger) but if you do have time inserted video technology, use this in preference. Should you require advice on how to go about this, please contact me at; dave4gee (AT) yahoo.com.au
Should you observe a positive event, please contact me and I will direct you to the proper reporting person and their email address.
Clear skies
First off, let us define what is a high quality asteroid prediction, and in no particular order the attributes are;
- Reasonably bright star – a star brighter than mag. 12 is considered helpful.
- Asteroid fainter than star – it always helps to have the asteroid fainter than the star because then the magnitude drop when the even occurs is large, and this makes the event easier to see. In the case of the three events, all have mag.-drop of 2 or more.
- Event duration grater than 2 seconds – this helps to distinguish atmospheric scintillation from a real event.
- Error in time less than 5 seconds – this helps because we know with certainty that the event will occur at a certain time and we don’t have to watch the star for minutes at a time.
- IOTA Rank greater than 90 – IOTA ranks all event on a scale up to 100, where an event of 100 means that if an observer is sited between the bold path lines shown on the map, then they almost certainly will see the event.
- The event has extremely high value because the data obtained from the observations will directly aid space exploration. The 29th June Pluto event falls into this category. More on this later.
Lets discuss the events in detail. (refer to the Occult prediction maps).
5th June : (212) Medea occults TYC 0604-1157
This event occurs at 19:04:22 UT = 5:04:22 am on Saturday morning. The star is mag. 11 and the asteroid is mag. 14, so the mag.-drop is 3.1, making this easy for visual observers.
The southern limit crosses Sydney CBD, so any sites to the north-west, like Linden Observatory will benefit with greater event certainty.
The star and asteroid will be at alt. of 32° and az. of 52° at event time.
Steve Preston (of IOTA) has sourced the star position from the URAT1 catalogue, so we can be assured that the star position coordinates are the best available.
19th June : (420) Berthholda occults TYC 628-01716
This event occurs at 14:33:57 UT
= 12:33:57 am on Saturday morning. The star is mag. 11.6 and the asteroid is mag. 13.4, so the mag. drop is 2.0, and it is still in the realm of the visual observer.
The path is centred on Sutherland, and extends from Gosford to Moss Vale, so anywhere between those limits will see the event.
The star and asteroid will be at alt. of 74° and az. of 14° at event time.
Steve Preston (of IOTA) has sourced the star position from the URAT1 catalogue, so we can be assured that the star position coordinates are the best available.
29th June : Pluto Occults 4 UCAC 347-165728
This event occurs at 16:48:40 UT
= 2:48:40 am on Tuesday morning. The star is mag. 12 and the Dwarf planet is mag. 14, so the mag. drop is 2.2, and it is still in the realm of the visual observer, however the disappearance and reappearance events will be gradual, taking many seconds to occur, due to Pluto’s atmosphere.
The predicted path, obtained using the UCAC4 catalogue and the Pluto DE432 ephemeris, covers almost all of Australia, however we expect updates from The RIO Group (Felipe Braga Ribas et al) leading up to the event. The RIO Group perform precise astronomy on the target star and Pluto and produce high quality predictions.
Any positive observations from this event could benefit the New Horizons flyby.
Marc Buie of The Southwest Research Institute writes;
It's (the occultation) going to be a very important with its occurrence so close to the New Horizons flyby and it's own occultation experiments. It's also nice that the star is bright (and red).
One goal for this event will be to go for extra density coverage on the central flash if that part of the shadow is accessible over land.
This prediction work, when completed, will be distributed to everyone with any interest in this event. I expect Bruno and Felipe will be crucial to getting the word out.
I wish I could be in the field with everyone to observe this for myself but I'll be tied up in Baltimore with all the activities surrounding the New Horizons encounter with Pluto. I'm on the hazard team that is on the lookout for dangerous stuff on the way in. It's going to be a crazy-busy but exciting time.
--Marc
So I encourage all observers to monitor these three events. I have indicated that all three events are observable visually (with telescopes 8” or larger) but if you do have time inserted video technology, use this in preference. Should you require advice on how to go about this, please contact me at; dave4gee (AT) yahoo.com.au
Should you observe a positive event, please contact me and I will direct you to the proper reporting person and their email address.
Clear skies