1. for Lomonosov-GRB collaboration
Results of the Multimessenger GRB Observations in the Lomonosov Mission
Vitaly Bogomolov,
for Lomonosov-GRB collaboration

2. “LOMONOSOV” SPACE MISSION
Was launched 28/04/2016
Scientific objectives:
Study of ultra-high energy cosmic rays
phenomena in hard x-rays and soft gamma-rays ( MeV)
Search and detection of optical transients accompanying gamma-ray bursts
study of transient luminosity events in the Earth atmosphere
magnetosphere physics research

3. Parameters of “Lomonosov” mission:
Orbit: ~500 km, polar
Mass: spacecraft ~600kg,
payload ~150kg
Total power ~ 300W
Data amount ~3Gb/day
Launch date – 28/04/2016
Complex of instruments:
BDRG – gamma spectrometer
SHOK – wide field optical camera
UFFO – coding mask x-ray telescope + UV telescope
TUS – Telescope for detecting flashes in atmosphere produced by cosmic rays with E>5*10^19 eV and TLEs
DEPRON, ELFIN-L – particle detectors

4. Instrument BDRG onboard “Lomonosov”
BDRG instrument consists of 3 similar detector boxes, connected to data analysis box.
Parameters of each BDRG box:
Detector: 3mm NaI(Tl) /17 mm CsI(Tl)
Sensitive area: 130mm
Energy range: – 3 MeV
Sensitivity for GRBs 10-7 erg/sm2
GRB localization- ~2о for bright GRBs
Goals of BDRG:
1. Production of GRB trigger
2. Spectral measurements and timing of GRB
in hard x-ray and gamma range
3. Estimation of GRB coordinates
4. X-ray and gamma-ray monitoring
5. Study of TGFs

5. Structure and amount of information from BDRG
3 detector boxes
Type of frame
Time interval between frames
Data amount, Mb
Continuous (180 Mb per day)
Monitoring
100ms
87 per day
Spectrum
15s
48 per day
Event mode
50 per day
Burst mode for fast/slow burst (5 Mb per burst)
1-10 ms
1.6 per burst
1-10 s
Not regular,
up to 106 events
The day portion of BDRG data is about Mb

6. Parameters of SHOK optical cameras for “Lomonosov” space mission
Two identical SHOK boxes with wide-field cameras and processor unit for image analysis are used. Each SHOK unit is a fast-acting wide-angle camera, which provide recording of optical emission with maximum magnitude of 9−10m at a single frame and exposure time of 0.2 seconds
Parameters of each SHOK box:
FOV: 20o x 40o
Time resolution: 0.2s
Sensitivity: 10 st. mag (in 200ms frame)
Mass ~5kg
Power ~27W (used by camera and powerful internal processor)
Photo of optical camera used in SHOK instrument

7. Data from SHOK optical cameras
transferred to ground
Two kinds of data are collected
For each GRB pictures taken from ~1min before trigger to ~2 min after trigger with time interval 0.2s are transferred (total FOV frames). Amount of data is ~700Mb per GRB
Between GRB triggers the difference between neighbor frames will be analyzed and parts of FOV (several degrees) with most significant changes are transferred. Most of such events are expected to be connected with some near Earth objects.

8. Production of GRB trigger
Several time scales for independent triggering:
10 ms interval, 1 ms resolution of transmitted data (“Fast”)
1 s interval, 10 ms resolution of transmitted data (“Slow”)
20 s interval, enlarged event mode transmitted data (“SuperSlow”)
2-Levels of trigger
Internal trigger: only BDRG data fixation
Alert trigger: Trigger for ShOK and messages via GlobalStar modem
Main mode: BDRG1  SHOK1 (any or if source in camera FOV)
BDRG2  SHOK2 (any or if source in camera FOV)
Redundant mode: BDRG1  SHOK1, SHOK2
BDRG2  SHOK1, SHOK2
BDRG3  SHOK1, SHOK2
System is operating this way

9. BDRG background conditions for GRB triggering

10. GRB catalog N GRB date GRB time GRB name Duration, s detectors
Most illuminated
BDRG triggers
Range, keV
GCN circulars 1
11:13:56
GRB160607A 10
100 - 2
12:10:02
GRB160703A 42
010
10-300
19725 3
17:40:19
011
30-300 4
18:23:55
GRB160720A 87
01X
slow, sslow
10-800
19728 5
6:13:30
GRB160802A 20
slow
20-300
19759 6
21:12:42
GRB160814A 70
X11
20-170 7
14:21:07
GRB160824B
111
19884 8
5:17:06
GRB160908A 30
X1X
10-170 9
14:07:55
11X
8:24:09 21
10X
60-900 11
22:51:12 12
101
19989
10:56:12
sslow
19992 13
11:30:20
GRB160917A 25
19990 14
17:03:06
GRB161015A 15
17:52:17
GRB161017A
110
20075 16
11:57:55
GRB A
20154 17
6:11:45
GRB A
35-300
20165 18
2:26:12
GRB А
20359 19
2:47:22
GRB В
20360

11. Statistics of GRBs observed by BDRG/Lomonosov
Probability to detect a GRB listed in GCN is ~20% (taking into account shadowing by the Earth and excluding the RB regions)
Probability to detect a GRB not listed in GCN is less than 10%

12. Example of GRB observed near RB in the equator region

13. GRB161017A
BDRG-2 NaI(Tl) counting rate time profiles in keV energy range with different time resolution. The top panel is the light curve fragment with 100 ms time resolution. The middle panel is the detailed light curve around the most intensive peak (corresponding time interval is marked by red line on the top panel). The bottom panel is the light curve with 10 ms time resolution in the interval marked by red line on the middle panel, t-t0 means the time after trigger

14. Robotic telescope network MASTER (from SAI MSU)

15. 17:55:38 --- Detection of OT at 4 pare pf frames, OT confirmation
17:54: forth image (30)
17:54: detection of OT at 3 pare of frames
17:52: notice to telescopes
17:52: first observation
MASTER-Amur (10s)
17:53: second image MASTER-Amur (10s)
17:51: Swift trigger
17:53: third image (20)
17:55: notice to GCN from MASTER
18:04: notice to GCN from Swift

16. GRB 161017A observations by Lomonosov/BDRG and MASTER

17. Common Lomonosov, MASTER-net and Swift observations of GRB A in broad bads from optics to gamma: light curve

18. Energy spectrum of GRB A in broad bads from optics to gamma observed by Lomonosov, MASTER-net and Swift

19. Thank You!

20. Accuracy of GRB localization from BDRG data
Standard formula for cosine shape of FOV: Here cos 1 ,, cos 2 and cos 3 are cosines of the angles between the axis of correspondent BDRG box and the GRB direction.
Result of laboratory test with 241Am source
Dependence on fluence, kT and background rate
(the results of Geant numeric modeling)
Slow GRB triggers (20s time of analysis) were produced by fast placing of 241Am ~130 cm above BDRG detectors and ~53 cm far from axis of the system.
Count rate from the source was approximately equal to background one in the keV channel chosen for GRB triggering (~30 s-1 for each detector)

21. Problem of GRB triggering on low polar orbit: triggering on electron precipitations

22. BDRG: examples of light curves