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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

3739 results found.

  1. EP260210a: Optical upper limits with Kinder observations
  2. EP260210a: SVOM/VT optical upper limit
  3. Fermi GRB 260209A: Global MASTER-Net observations report
  4. GRB 260208B: SVOM/VT optical candidate
  5. GRB 260209A: Fermi GBM Final Real-time Localization
  6. GRB 260208A: SVOM/VT optical observation
  7. Fermi GRB 260208A: Global MASTER-Net observations report
  8. GRB 260206A: Swift-XRT observations
  9. GRB 260206A: Tiled Swift observations
  10. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  11. GRB 260204A : MASTER Global robotic net optical observations
  12. GRID detection of GRB 260131A/B
  13. GRB 260131A/B: EP/FXT X-ray afterglow detection
  14. GRB 260131A: NOT spectroscopic redshift z = 1.434
  15. Konus-Wind detection of GRB 260131A/B
  16. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  17. GRB 260131A/B: Fermi GBM Observation
  18. GRB 260131B: MAXI/GSC detection
  19. Fermi GRB 260129A: Global MASTER-Net observations report
  20. GRB 260129B: Fermi GBM Final Localization
  21. GRB 260127B: GOTO candidate optical counterpart
  22. GRB 260122B: Swift-BAT refined analysis
  23. GRB 260120B: Swift-BAT refined analysis
  24. SVOM GRB260121.06: Global MASTER-Net observations report
  25. Fermi trigger No 790570272: Global MASTER-Net observations report
  26. EP260119a: Global MASTER-Net observations report
  27. The EP-WXT trigger 01709251266 is likely a flaring star
  28. EP260110a: SVOM/C-GFT upper limit
  29. GRB 260104A: Swift-BAT refined analysis
  30. GRB 260101A: Swift-BAT refined analysis
  31. Fermi GRB 260107A: Global MASTER-Net observations report
  32. GRB 260107A: Fermi GBM Final Real-time Localization
  33. Fermi GRB 260105A: Global MASTER-Net observations report
  34. EP260105a: Global MASTER-Net observations report
  35. GRB 260104C: Fermi GBM Final Real-time Localization
  36. Fermi GRB 260104B: Global MASTER-Net observations report
  37. SVOM GRB260103.08: Global MASTER-Net observations report
  38. EP260101a: Global MASTER-Net observations report
  39. GRB 260101A: Swift detection of a burst with an optical counterpart
  40. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  41. Fermi GRB 251228A: Global MASTER-Net observations report
  42. SVOM GRB251227.07: Global MASTER-Net observations report
  43. IceCube Alert 251225.84: Global MASTER-Net observations report
  44. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  45. GRB 251220A: MAXI/GSC detection
  46. IceCube Alert 251218.85: Global MASTER-Net observations report
  47. Fermi GRB 251217A: Global MASTER-Net observations report
  48. Fermi GRB 251215A: Global MASTER-Net observations report
  49. GRB 251214B: UAFO optical upper limit
  50. GRB 251202A: radio detection with the VLA
  51. EP251214b: Global MASTER-Net observations report
  52. GRB 251214B: LCO detection of the optical counterpart
  53. EP251214a: Global MASTER-Net observations report
  54. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  55. GRB 251209A: Fermi GBM observation
  56. Fermi GRB 251208C: Global MASTER-Net observations report
  57. GRB 251208B: GROWTH-India Telescope optical upper limits
  58. GRB 251208A: Fermi GBM Final Real-time Localization
  59. GRB 251205A: Liverpool Telescope further optical follow-up observations
  60. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  61. GRB 251205A: Swift detection of a burst with an optical afterglow
  62. GRB 251126B: Fermi GBM Final Localization
  63. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  64. GRB 251201A: GECAM-B observation of a burst
  65. EP251129a/GRB 251129A: NOWT Detection
  66. GRB 251201A: SVOM/GRM observation of a burst
  67. Swift GRB 251201B : MASTER optical counterpart detection
  68. Swift GRB 251201B: Global MASTER-Net observations report
  69. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  70. GRB 251201A: MAXI/GSC detection
  71. SVOM GRB 251129A : MASTER optical counterpart detection
  72. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  73. GRB 251129A: Correction to the position of the optical counterpar
  74. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  75. SVOM GRB251129A: Global MASTER-Net observations report
  76. GRB 251126A: Swift-BAT refined analysis
  77. GRB 251126A: Mondy and SAO RAS optical observations
  78. Fermi GRB 251125B: Global MASTER-Net observations report
  79. EP251118A: 3.6m DOT optical afterglow detection
  80. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  82. EP251122a: Global MASTER-Net observations report
  83. GRB 251122A / EP251122a: SVOM detection of a long burst
  84. EP251118A / GRB 251118C : MASTER optical counterpart observations
  85. EP251118a: Global MASTER-Net observations report
  86. LAT GRB251118.86: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  88. GRB 251116C: SVOM/ECLAIRs refined analysis
  89. LAT GRB251117.51: Global MASTER-Net observations report
  90. GRB 251116C: Swift/BAT arcminute localization of a burst
  91. GRB 251116C: SVOM detection of a burst
  92. GRB 251112A: Swift-BAT refined analysis
  93. Fermi GRB 251114A: Global MASTER-Net observations report
  94. GRB 251112B: MAXI/GSC detection
  95. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  97. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  98. GRB 251111A: SVOM/VT optical observations with X-band data
  99. GRB 251111A: SVOM/VT optical observations with VHF data
  100. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate

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