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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"

26922 results found.

  1. GRB 260726A: SVOM/VT optical candidate
  2. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  3. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  4. EP260723a: SVOM/ECLAIRs Upper Limit
  5. GRB 260727A: GOTO early optical upper limit
  6. GRB 260727A: Kilonova-Catcher optical upper limit
  7. GRB 260727A: LCO optical upper limits
  8. GRB 260727B: Fermi GBM Final Real-time Localization
  9. Fermi GRB 260726A: Global MASTER-Net observations report
  10. GRB 260727A: SVOM detection of a bright long burst
  11. GRB 260726A: SVOM detection of a burst
  12. GRB 260726A: Fermi GBM Final Real-time Localization
  13. EP260723a: further EP-FXT follow-up observation
  14. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  15. EP260725a: EP-WXT detection of an X-ray transient
  16. EP260723a: EP-FXT follow-up observation
  17. GRB 260718A: SVOM/ECLAIRs refined analysis
  18. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  19. EP260723a: SVOM/VT optical observation
  20. EP260723a: COLIBRÍ optical observations
  21. EP260723a: NOT optical conterpart confirmation
  22. EP260723a: EP-WXT detection of a fast X-ray transient
  23. GRB 260723A: Fermi GBM Final Localization
  24. IceCube Alert 260722A: Global MASTER-Net observations report
  25. GRB 260722A: Fermi GBM Final Real-time Localization
  26. Fermi GBM trigger 806384210/260722151 is not a GRB
  27. GRB 260721A: NuSTAR detection of prompt emission
  28. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  29. GRB 260705A: Retraction of optical counterpart
  30. GRB 260718A: EP-FXT follow-up observation
  31. Fermi trigger No 806104130: Global MASTER-Net observations report
  32. Fermi GRB 260718A: Global MASTER-Net observations report
  33. GRB 260718A: LCO optical upper limits
  34. GRB 260711A: SVOM/GRM observation
  35. GRB 260710A: SVOM/GRM observation
  36. GRB 260718A: Fermi GBM Observation
  37. GRB 260718A : GRANDMA and KNC upper limits
  38. GRB 260718A: SVOM/VT optical upper limits
  39. GRB 260718A: SVOM/VT optical upper limits from VHF data
  40. GRB 260718A: SVOM detection of a burst
  41. GRB 260714B: SVOM/GRM observation
  42. GRB 260714B: GECAM-B observation of a burst
  43. GRB 260618B: EP-FXT follow-up observation upper limit
  44. GRB 260714B: COLIBRÍ optical counterpart candidate
  45. SVOM sb26071506: Global MASTER-Net observations report
  46. sb26071506: SVOM detection of a X-ray transient
  47. GRB 260715A: Fermi GBM Final Real-time Localization
  48. EP260703a: SVOM/ECLAIRs Upper Limit
  49. GRB 260714B: Fermi-LAT detection
  50. GRB 260714B: Fermi GBM Detection
  51. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  52. GRB 260714B: Fermi GBM Final Real-time Localization
  53. GRB 260705A: ATCA radio observations
  54. GRB 260714A: Fermi GBM Final Real-time Localization
  55. EP260713a: Einstein Probe detection of an X-ray transient
  56. GRB 260619A: SVOM/VT continuous optical observations
  57. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  58. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  59. EP260711a: EP-FXT follow-up observation
  60. GRB 260708A: GRANDMA Optical Observations
  61. GRB 260708A: LCO optical observations
  62. EP260711a: Einstein Probe detection of an X-ray transient
  63. GRB 260710A: Fermi GBM Detection
  64. GRB 260709A: SVOM/GRM detection
  65. GRB 260709A: GECAM-B observation
  66. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  67. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  68. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  69. GRB 260710A: Fermi GBM Final Real-time Localization
  70. GRB 260704A: SVOM/ECLAIRs refined analysis
  71. GRB 260706A : GRANDMA Upper limits
  72. GRB 260708A: Kilonova-Catcher optical afterglow detection
  73. GRB 260708A: GECAM-B observation of a burst
  74. GRB 260708A: Fermi-GBM observation
  75. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  76. IceCube Alert 260709A: Global MASTER-Net observations report
  77. GRB 260709A: Fermi GBM Final Real-time Localization
  78. LAT GRB260708.42: Global MASTER-Net observations report
  79. GRB 260708A: Fermi-LAT detection
  80. GRB 260705B: SVOM/GRM observation
  81. GRB 260708A: Fermi-GBM detection
  82. GRB 260706A: Further EP-FXT follow-up observation
  83. GRB 260706A: SVOM/VT optical upper limits
  84. EP260707a is not a real source
  85. EP260707a: LCOGT Optical Upper Limit
  86. EP260707a: TRT optical upper limit
  87. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  88. EP260707a: Einstein Probe detection of an X-ray transient
  89. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  90. GRB 260706A: SVOM/ECLAIRs refined analysis
  91. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  92. GRB 260706A: SVOM/GRM observation
  93. GRB 260706A: REM optical/NIR observations
  94. GRB 260706A: LCO optical upper limit
  95. GRB 260706A: EP-FXT follow-up observation
  96. GRB 260707A: Fermi GBM Final Real-time Localization
  97. The EP-WXT trigger 01709274151 is likely a flaring star
  98. The EP-WXT trigger 01709274141 is likely a flaring star
  99. GRB 260706A: Fermi GBM Observation
  100. GRB 260705A: SVOM/ECLAIRs refined analysis

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