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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"

5516 results found.

  1. EP250108a: Liverpool Telescope likely optical counterpart
  2. EP250109a: GOTO optical upper limits
  3. GRB 250103A: 1.6m Mephisto optical observations
  4. GRB 250103A: Swift-XRT afterglow detection
  5. Fermi GRB 250107B: Global MASTER-Net observations report
  6. Fermi trigger No 757753930: Global MASTER-Net observations report
  7. GRB 250103B: Swift-XRT refined Analysis
  8. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  9. GRB 250103A: Swift-XRT observations
  10. GRB 250103B：SVOM/VT optical counterpart
  11. GRB 250103A: Montarrenti Observatory optical detection
  12. GRB 250101A: further LCOGT optical afterglow observations
  13. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  14. GRB 250103A: TSHAO optical upper limit
  15. GRB 250103A: Fermi GBM Observation
  16. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  17. Swift GRB 250103B: Global MASTER-Net observations report
  18. GRB 250101a: Liverpool Telescope optical follow-up
  19. GRB 250103B: SVOM detection of a long burst
  20. GRB 250103A: Xinglong 2.16m Optical Candidate
  21. Fermi GRB 250102A: Global MASTER-Net observations report
  22. GRB 250103A: GOTO optical upper limit
  23. IceCube Alert 250102.58: Global MASTER-Net observations report
  24. GRB 250101A: LCO optical counterpart detection
  25. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  26. Konus-Wind detection of GRB 241228A
  27. GRB 241229A: GOTO optical upper limits
  28. Fermi GRB 241228B: Global MASTER-Net observations report
  29. GRB 241228A: Fermi GBM Observation
  30. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  31. GRB 241228A: Swift detection of a burst
  32. Fermi trigger No 756678579: Global MASTER-Net observations report
  33. EP241223a: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 241204A (short/hard)
  35. GRB 241217A/EP241217b: REM optical/NIR upper limits
  36. GRB 241218a: Liverpool Telescope optical follow-up
  37. EP241217a: Liverpool Telescope optical follow-up
  38. GRB 241218A: LCOGT Optical Upper Limit
  39. EP241217a: Global MASTER-Net observations report
  40. EP241217A: Non-detection from Fermi-GBM Observations
  41. GRB 241214A: GRBAlpha detection
  42. EP241217a: Gemini-North detection of the likely optical counterpart
  43. EP241217a: EP detection of an X-ray transient
  44. GRB 241213B: MAXI/GSC detection
  45. GRB 241213A: REM optical/NIR upper limits
  46. GRB 241212A : SVOM/VT bright optical afterglow
  47. Konus-Wind detection of GRB 241209B
  48. GRB 241209B: GRBAlpha detection
  49. GRB 241206C: GRBAlpha detection
  50. Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
  51. EP241208a: Global MASTER-Net observations report
  52. Fermi trigger No 755485387: Global MASTER-Net observations report
  53. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  54. Fermi GRB 241209C: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  56. Fermi GRB 241209A: Global MASTER-Net observations report
  57. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  58. Fermi GRB 241207B: Global MASTER-Net observations report
  59. Fermi GRB 241207A: Global MASTER-Net observations report
  60. GRB 241206C: SVOM/GRM observation of a likely short burst
  61. GRB 241204A: DDOTI Upper Limits on the Afterglow
  62. GRB 241204A: Fermi GBM Observation
  63. Fermi GRB 241204A: Global MASTER-Net observations report
  64. GRB 241204A: Fermi-LAT detection
  65. EP241202b: Kinder optical counterpart candidate
  66. EP241202b: Global MASTER-Net observations report
  67. EP241201a: Kinder optical counterpart candidate
  68. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  69. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  70. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  71. EP241126a: GSP detects optical counterpart
  72. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  73. Konus-Wind detection of GRB 241117A
  74. IPN triangulation of GRB 241117A
  75. GRB 241114B: Insight-HXMT/HE detection
  76. Fermi GRB 241118A: Global MASTER-Net observations report
  77. GRB 241117A: Fermi GBM Detection
  78. Fermi GRB 241117A: Global MASTER-Net observations report
  79. GRB 241117A: Fermi GBM Final Real-time Localization
  80. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  81. EP241113a: Swift XRT weak detection
  82. GRB 241113A: J-band observations with WINTER
  83. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  84. GRB 241113A: KAIT optical observations
  85. EP241113b: Global MASTER-Net observations report
  86. GRB 241113A: REM detection of the optical/NIR afterglow
  87. Fermi trigger No 753166198: Global MASTER-Net observations report
  88. GRB 241112B: AbAO optical upper limit
  89. IPN triangulation of GRB 241107A (short/hard)
  90. Fermi trigger No 752878030: Global MASTER-Net observations report
  91. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  93. EP241107a: AKO Optical Afterglow Follow-Up Observations
  94. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  95. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  96. EP241107a: AKO Optical Afterglow Detection
  97. EP241101a: CrAO ZTSH optical observations
  98. GRB 241030A: Mondy optical observations
  99. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  100. GRB 240511A: LCO upper limits

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