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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"

27201 results found.

  1. GRB 260818B: Further EP-FXT observation
  2. GRB 260818B: VLT optical and nIR observations
  3. GRB 260818B: TNG NIR observations
  4. MAXI GRB260827.40: Global MASTER-Net observations report
  5. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  6. GRB 260827A: Fermi GBM Final Real-time Localization
  7. GRB 260818B: 6 GHz VLA observations
  8. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  9. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. EP260822a: Global MASTER-Net observations report
  11. EP Alert 260820.31: Global MASTER-Net observations report
  12. GRB 260807A: EP-FXT follow-up observations
  13. GRB 260822A: SVOM/ECLAIRs refined analysis
  14. GRB 260809A: SVOM/ECLAIRs refined analysis
  15. IceCube Alert 260825A: Global MASTER-Net observations report
  16. GRB 260825A: Fermi GBM Final Real-time Localization
  17. GRB 260822A: EP/FXT follow-up observations
  18. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  19. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  20. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  21. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  22. GRB 260822A: LCO optical upper limits
  23. The EP-WXT trigger 01709287395 is likely a flaring star
  24. GRB260822B: Fermi GBM Final Localization
  25. GRB 260822A: GROWTH-India Telescope Upper Limits
  26. GRB 260822A: GOTO optical upper limit
  27. GRB 260822A: SVOM detection of a short burst
  28. GRB 260818B: SVOM/C-GFT optical upper limit
  29. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  30. IceCube Alert 260821A: Global MASTER-Net observations report
  31. The EP-WXT trigger 01709286204 is likely a flaring star
  32. GRB260820A: Fermi GBM Final Real-Time Localization
  33. GRB 260818B: EP-FXT follow-up observation
  34. GRB 260818A: J-band observations with WINTER
  35. GRB 260818B: SVOM/ECLAIRs refined analysis
  36. GRB 260818A: SVOM/ECLAIRs refined analysis
  37. GRB 260818B: NOT optical upper limits
  38. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  39. GRB260818A: EP-FXT follow-up observation
  40. GRB 260818B: LCO optical upper limits
  41. GRB 260818B: SVOM detection of a short burst
  42. SVOM trigger sb26081806 is not a GRB
  43. EP260806a: SAO RAS multicolor optical observations
  44. GRB 260818A: LCO optical upper limits
  45. EP260812a: AbAO optical upper limit
  46. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB 260818A: SVOM possible detection of a long and faint GRB
  48. EP260806a: SVOM/ECLAIRs detection through targeted search
  49. The EP-WXT trigger 01709281429 is likely a flaring star
  50. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  51. EP260806a: WFST optical observations
  52. The EP-WXT trigger 01709280562 is likely a flaring star
  53. The EP-WXT trigger 01709279838 is likely a flaring star
  54. GRB 260808B: Liverpool Telescope further optical observations
  55. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  56. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  57. GRB 260813A: Fermi GBM Final Real-time Localization
  58. EP260812a: NOT and Liverpool Telescope upper limits:
  59. EP260812a: SVOM/C-GFT optical upper limit
  60. EP260812b: COLIBRÍ optical observations
  61. EP260812b: SVOM/VT optical observation
  62. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  63. Fermi GBM Sub-Threshold Detection of GRB 260809A
  64. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  65. GRB 260808B: SVOM/VT optical re-brightening at day 3
  66. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  67. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  68. GRB 260807A: SVOM/ECLAIRs refined analysis
  69. GRB260808B: MAO/AZT-22 optical observations
  70. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  71. GRB 260809A: J-band upper limit with WINTER
  72. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  73. GRB 260806A: Glowbug gamma-ray detection
  74. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  75. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  76. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  77. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  78. The EP-WXT trigger 01709278015 is likely a flaring star
  79. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  80. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  81. GRB 260809A: NOT optical observations
  82. GRB260809A: MAO/AZT-22 optical observations
  83. GRB260809A: OHP/T193 optical observations
  84. GRB 260809A: SVOM/VT optical counterpart
  85. EP260809a: J-band upper limit with WINTER
  86. GRB 260808B: J-band upper limit with WINTER
  87. GRB 260808B: SVOM/ECLAIRs refined analysis
  88. GRB 260809A: SVOM detection of a faint burst
  89. GRB 260808B: Liverpool Telescope optical observations
  90. GRB 260808B: NOT optical observations
  91. GRB 260808B: LCO optical observations
  92. EP260809a: COLIBRÍ optical observations
  93. EP260809a: LCO optical observation
  94. EP260809a: OHP/T193 optical observations
  95. GRB260808B: OHP/T193 optical observations
  96. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  97. GRB 260808B: SVOM/VT optical afterglow confirmation
  98. GRB 260808C: Fermi GBM Final Real-time Localization
  99. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  100. GRB 260808B: SVOM/VT optical candidate from VHF data

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