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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"

25013 results found.

  1. GRB 241018A/sb24101802: Mephisto optical upper limit
  2. GRB 241017A/sb24101702: Mephisto optical upper limit
  3. GRB 241018A: Mondy optical upper limit
  4. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  5. GRB 241018A: GROWTH-India telescope optical upper limit
  6. GRB241018A: XingLong Optical Upper Limit
  7. GRB 241018A: Swift-XRT observations
  8. GRB 241018A: REM optical/NIR upper limits
  9. GRB 241018A: NOT optical observations
  10. GRB 241018A: SVOM/VT follow-up and optical candidate
  11. GRB 241018A: LCO/0.4m optical upper limits
  12. GRB 241006A: VIRT Optical Upper Limit
  13. GRB 240727A: VIRT Optical Upper Limit
  14. GRB 241018A: X-ray afterglow candidate observed by MXT
  15. GRB 241017A: Swift-XRT observations
  16. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  17. GRB 241001A: EP-FXT afterglow detection
  18. GRB 241017A: GROWTH-India Telescope optical upper limit
  19. GRB241017A: TOO Observations by SVOM/MXT
  20. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  21. GRB 241017A: J-band upper limit from WINTER
  22. GRB 241016B: SVOM/GRM observation
  23. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  24. GRB 241010A: Swift-BAT refined analysis
  25. GRB 241013B: Fermi GBM Observation
  26. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  27. GRB 241013A: Fermi GBM Observation
  28. GRB 240916A: radio detection with the VLA
  29. GRB241013A: REM observations
  30. GRB 241009A: LCO optical upper limits
  31. Integral GRB241013.04: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  33. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  34. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  35. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  36. GRB 241009A: GRANDMA optical upper limits
  37. GRB 241009A: Swift-XRT afterglow detection
  38. GRB 241010A: JinShan optical observations and potential host galaxy
  39. GRB 241010A: Swift-XRT refined Analysis
  40. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  41. Fermi trigger No 750211959: Global MASTER-Net observations report
  42. Fermi trigger No 750291012: Global MASTER-Net observations report
  43. GRB 241010A: J-band observations with WINTER
  44. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  45. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 241010A: Enhanced Swift-XRT position
  47. GRB 241010A: LCO optical observations
  48. GRB 241010A: Swift detection of a burst with an optical counterpart
  49. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  50. GRB 241006A: Swift-BAT refined analysis
  51. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  52. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  53. GRB 241008A: Fermi GBM Observation
  54. GRB 241002B: Swift-XRT afterglow detection
  55. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  56. GRB 241002A: NOT optical upper limits
  57. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  58. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  59. IceCube-241006A: No candidates from the Zwicky Transient Facility
  60. GRB 241006A: GRANDMA optical upper limits
  61. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  62. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  63. GRB 240910A: LBT optical observations
  64. GRB 241006A: Swift-XRT refined Analysis
  65. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  66. GRB 241006A: PRIME near-infrared upper limits
  67. GRB 241006A: Swift/UVOT Upper Limits
  68. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  69. GRB 241001A: Swift-XRT afterglow detection
  70. GRB 241006A: Enhanced Swift-XRT position
  71. GRB 241006A: Swift detection of a burst
  72. GRB 240930B: SVOM/C-GFT optical upper limit
  73. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  74. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  75. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  76. GRB 241002B: Fermi GBM Observation
  77. GRB 241002B: Swift-XRT observations
  78. GRB 241002C: SVOM/C-GFT optical upper limit
  79. GRB 241002A: Swift-BAT refined analysis
  80. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  81. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  82. GRB 241002B: PRIME near-infrared detection
  83. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  84. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  85. IPN triangulation of GRB 240930B / EP 240930a
  86. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  87. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  88. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  89. GRB 241002C : MITSuME Akeno optical upper limits
  90. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  91. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  92. GRB241001A: REM optical/NIR upper limits
  93. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  94. GRB 241002A: Swift/UVOT Upper Limits
  95. EP240930a: Liverpool Telescope observations
  96. GRB 241002A: Swift-XRT refined Analysis
  97. GRB 241002A: LCOGT Optical Upper Limits
  98. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  99. GRB 241001A: Swift/UVOT Detection
  100. GRB 240929A: Liverpool Telescope prompt followup observations

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