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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"

3674 results found.

  1. EP260128a: Liverpool Telescope optical observations and possible counterpart
  2. EP260128a: Global MASTER-Net observations report
  3. Fermi GRB 260127A: Global MASTER-Net observations report
  4. GRB 260127A: COLIBRÍ optical observations
  5. GRB 260127B: GOTO candidate optical counterpart
  6. Fermi GRB 260125B: Global MASTER-Net observations report
  7. SVOM GRB260121.06: Global MASTER-Net observations report
  8. GRB 260101A: 239Alferov CubeSat detection
  9. Fermi trigger No 790601190: Global MASTER-Net observations report
  10. EP260119a: Global MASTER-Net observations report
  11. GRB 260110A: SVOM detection of a burst through offline search
  12. SVOM GRB260117.82: Global MASTER-Net observations report
  13. Swift triggered on the HMXB 1A 1118-61
  14. GRB 251222A: radio detection with the VLA
  15. Swift GRB 260114A: Global MASTER-Net observations report
  16. Fermi GRB 260105A: Global MASTER-Net observations report
  17. Fermi GRB 260105B: Global MASTER-Net observations report
  18. EP260104a: Global MASTER-Net observations report
  19. EP260105a: Global MASTER-Net observations report
  20. Fermi GRB 260104B: Global MASTER-Net observations report
  21. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  22. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  23. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  24. Fermi GRB 251228A: Global MASTER-Net observations report
  25. GRB 251228A: Fermi GBM Final Real-time Localization
  26. SVOM GRB251227.07: Global MASTER-Net observations report
  27. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  28. EP251222a: Global MASTER-Net observations report
  29. GRB 251222A: 1.3m DFOT optical detection
  30. GRB251221A: 7DT optical upper limits
  31. EP251222b/GRB 251222A: SVOM/GRM observation
  32. GRB 251221A: Fermi GBM Observation
  33. GRB 251221A: Fermi GBM Final Real-time Localization
  34. EP251220a: Global MASTER-Net observations report
  35. IceCube Alert 251218.85: Global MASTER-Net observations report
  36. Fermi GRB 251216A: Global MASTER-Net observations report
  37. GRB 251214B: Mondy optical upper limit
  38. Fermi GRB 251215A: Global MASTER-Net observations report
  39. EP251214b: Global MASTER-Net observations report
  40. GRB 251214B: COLIBRÍ observations of the afterglow
  41. Fermi trigger No 787396657: Global MASTER-Net observations report
  42. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  43. IPN triangulation of GRB 251129B (short/hard)
  44. GRB 251130B: AstroSat CZTI detection
  45. GRB 251201B: Swift detection of a burst with an optical counterpart
  46. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  47. Fermi GRB 251130B: Global MASTER-Net observations report
  48. EP251130a: COLIBRÍ optical counterpart candidate
  49. GRB 251128A: AstroSat CZTI detection
  50. GRB 251126A: SAO RAS optical observations
  51. GRB 251128A: Fermi GBM Observation
  52. Fermi GRB 251128A: Global MASTER-Net observations report
  53. GRB 251126A: further SAO RAS optical observations
  54. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  55. GRB 251128A: Fermi GBM Final Real-time Localization
  56. Fermi GRB 251125A: Global MASTER-Net observations report
  57. EP251118a: Xinglong-2.16m optical observation
  58. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  59. GRB 251018A: FRAM-Auger optical detection
  60. LAT GRB251118.86: Global MASTER-Net observations report
  61. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  62. GRB 251115A: Swift-XRT observations
  63. GRB 251116C: Swift-XRT observations
  64. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  65. GRB 251116C: SVOM/VT optical upper limit
  66. GRB 251025B: further Mondy optical observations
  67. Fermi GRB 251115A: Global MASTER-Net observations report
  68. GRB 251112A: Swift-BAT refined analysis
  69. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  70. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  71. Fermi GRB 251114A: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  73. Swift Trigger 1413695: a possible GRB 251112A
  74. GRB 251111A: SVOM/VT optical observations with X-band data
  75. GRB 251105A: AstroSat CZTI detection
  76. SVOM GRB251108.54: Global MASTER-Net observations report
  77. SVOM GRB251106.83: Global MASTER-Net observations report
  78. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. GRB 251104A: SVOM detection of a burst
  80. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  81. Fermi GRB 251103A: Global MASTER-Net observations report
  82. Fermi GRB 251102A: Global MASTER-Net observations report
  83. GRB 251028A: Fermi GBM Observation
  84. GRB 251026B: LBT near-infrared observations
  85. GRB 251028B: Fermi/GBM observation
  86. GRB 251028B: Glowbug gamma-ray detection
  87. GRB 251028A: Glowbug gamma-ray detection
  88. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  89. Fermi GRB 251028B: Global MASTER-Net observations report
  90. GRB 251028B: Fermi GBM Final Localization Correction
  91. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  92. GRB 251028A: MAXI/GSC detection
  93. GRB 251028A: Fermi GBM Final Real-time Localization
  94. The EP-WXT trigger 01709247525 is not a real source
  95. EP251023b: Global MASTER-Net observations report
  96. Fermi GRB 251023A: Global MASTER-Net observations report
  97. EP/WXT 01709247295: GOTO optical afterglow candidate.
  98. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  99. EP251021b: Einstein Probe detection of a fast X-ray transient
  100. IceCube-251018A: Global MASTER-Net observations report

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