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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"

26374 results found.

  1. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  2. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  3. GRB 241115A: Mephisto upper limits
  4. GRB 241113B: Mephisto upper limits
  5. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  6. GRB 241115D / EP 241115a: SVOM/GRM observation
  7. EP241113a: Swift XRT weak detection
  8. GRB 241115A: Fermi GBM Observation
  9. GRB 241115A: LCOGT Optical Upper Limits
  10. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  11. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  12. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  13. EP241115a: EP detection of a fast X-ray transient
  14. Swift GRB 241115A: Global MASTER-Net observations report
  15. Fermi GRB 241115A: Global MASTER-Net observations report
  16. GRB 241115A: Swift detection of a burst
  17. EP 241113a: LBT possible optical counterpart
  18. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  19. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  20. GRB 241113A: Swift-BAT refined analysis
  21. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  22. GRB 241113A: PRIME near-infrared upper limits
  23. EP241113a: Global MASTER-Net observations report
  24. GRB 241113B: J-band upper limit from WINTER
  25. GRB 241113A: J-band observations with WINTER
  26. EP241113a : J-band observations with WINTER
  27. GRB 241030A: LCO optical observation
  28. GRB 241113B: Swift-XRT observations
  29. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  31. EP241113b/GRB 241113B: EP detection of GRB 241113B
  32. Fermi-LAT gamma-ray observations of IceCube-241113A
  33. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  34. GRB 241113A: Swift-XRT refined Analysis
  35. GRB 241113A: Swift/UVOT Detection
  36. GRB 241113A: REM detection of the optical/NIR afterglow
  37. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  38. GRB 241113A: LCO optical observations
  39. GRB 241112B: GMG Optical Upper Limit
  40. GRB 241113A: Enhanced Swift-XRT position
  41. GRB241113A: LCOGT (40-cm) optical counterpart detection
  42. GRB 241113A: Swift detection of a burst with an optical counterpart
  43. SVOM/GRM detection of a short burst from SGR 1E1841-045
  44. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  45. GRB 241112B: AbAO optical upper limit
  46. GRB 241107A: GROWTH-India telescope optical upper limit
  47. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  48. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  49. GRB 241112B: Swift-XRT afterglow detection
  50. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  51. GRB 241112B: Mephisto optical upper limits
  52. GRB 241112B: GOTO optical upper limits
  53. GRB 241107A: INTEGRAL IBIS localization
  54. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  55. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  56. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  57. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  58. IPN triangulation of GRB 241107A (short/hard)
  59. GRB 241025C: VZLUSAT-2 detection
  60. GRB 241025A: VZLUSAT-2 detection
  61. GRB 241018A: cubesat Avion detection
  62. GRB 241030B: TESS detection of optical counterpart
  63. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  64. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  65. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  67. Integral GRB241109.89: Global MASTER-Net observations report
  68. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  69. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  70. EP241107a: AbAO optical upper limit
  71. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  72. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  73. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  74. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  75. EP241109a: confirmation of a stellar flare by BOOTES-7
  76. GRB 241108A: Swift-XRT observations
  77. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  78. EP241107a: KAIT optical observations
  79. GRB 241030A: TESS observations
  80. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  81. EP241107a: Kinder optical follow-up observations
  82. GRB 241025A: radio detection with the VLA
  83. EP241107a: AKO Optical Afterglow Follow-Up Observations
  84. EP241107a: GSP detects optical counterpart
  85. GRB 241105A: SVOM/GRM observation
  86. EP241107a: OHP/T193 photometric and spectroscopic observations
  87. GRB 241105a: PRIME near-infrared upper limits
  88. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  89. EP241107a: GIT optical observations
  90. EP241107a: SVOM/C-GFT optical observations
  91. EP241107a: AKO Optical Afterglow Detection
  92. GRB 241025A: LBT optical observations
  93. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  94. GRB 241105A: Swift/UVOT Detection
  95. GRB 241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  96. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  97. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  98. GRB 241105A: Swift-XRT afterglow detection
  99. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  100. GRB 241104A: Swift-XRT observations

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